Process for producing polydienes

ABSTRACT

A method for producing a polydiene, the method comprising of combining a lanthanide compound, an alkylating agent, a halogen source, and optionally conjugated diene monomer to form an active preformed catalyst; independent of step (i), introducing an amine with conjugated diene monomer to be polymerized; independent of step (i), introducing the active preformed catalyst to the conjugated diene monomer to be polymerized to form an active polymerization mixture, where the active polymerization mixture includes less than 10% by weight, based on the total weight of the active polymerization mixture, of a solvent; and allowing the monomer to be polymerized to polymerize in the presence of the amine.

This application is a continuation of U.S. National Stage applicationSer. No. 13/825,703, filed on Mar. 22, 2013, which claims the benefit ofPCT/US2011/051717, filed Sep. 15, 2011, and U.S. Provisional ApplicationNo. 61/385,742, filed Sep. 23, 2010, which are incorporated herein byreference.

FIELD OF THE INVENTION

One or more embodiments of the present invention relate to a method forproducing polydienes.

BACKGROUND OF THE INVENTION

Synthetically produced polymers such as polydienes are used in the artof manufacturing tires. Synthetic polymers that undergo strain-inducedcrystallization provide advantageous properties such as tensile strengthand abrasion resistance. Thus, cis-1,4-polydienes with highcis-1,4-linkage content, which exhibit the increased ability to undergostrain-induced crystallization, have been advantageously employed. Also,certain functionalized polymers have been used in the manufacture oftires to prepare vulcanizates that demonstrate reduced hysteresis, i.e.,less loss of mechanical energy to heat. It is believed that thefunctional group of the functionalized polymers reduces the number offree polymer chain ends via interaction with filler particles and mayalso reduce filler agglomeration. Thus, cis-1,4-polydienes haveadvantageously been functionalized to provide vulcanizates that undergostrain-induced crystallization and demonstrate reduced hysteresis. Theability to functionalize the polymer, particularly at its chain end,depends on the reactivity of the polymer. Typically, only a fraction ofthe polymer molecules in any given sample can be reacted withfunctionalizing agents. It is therefore desirable to develop a methodfor producing cis-1,4-polydienes having higher cis-1,4-linkage contentand a greater percentage of reactive chain ends for functionalization.

Polydienes may be produced by solution polymerization, whereinconjugated diene monomer is polymerized in an inert solvent or diluent.The solvent serves to solubilize the reactants and products, to act as acarrier for the reactants and product, to aid in the transfer of theheat of polymerization, and to help in moderating the polymerizationrate. The solvent also allows easier stirring and transferring of thepolymerization mixture (also called cement), since the viscosity of thecement is decreased by the presence of the solvent. Nevertheless, thepresence of solvent presents a number of difficulties. The solvent mustbe separated from the polymer and then recycled for reuse or otherwisedisposed of as waste. The cost of recovering and recycling the solventadds greatly to the cost of the polymer being produced, and there isalways the risk that the recycled solvent after purification may stillretain some impurities that will poison the polymerization catalyst. Inaddition, some solvents such as aromatic hydrocarbons can raiseenvironmental concerns. Further, the purity of the polymer product maybe affected if there are difficulties in removing the solvent.

Polydienes may also be produced by bulk polymerization (also called masspolymerization), wherein conjugated diene monomer is polymerized in theabsence or substantial absence of any solvent, and, in effect, themonomer itself acts as a diluent. Since bulk polymerization isessentially solventless, there is less contamination risk, and theproduct separation is simplified. Bulk polymerization offers a number ofeconomic advantages including lower capital cost for new plant capacity,lower energy cost to operate, and fewer people to operate. Thesolventless feature also provides environmental advantages, withemissions and waste water pollution being reduced.

Despite its many advantages, bulk polymerization requires very carefultemperature control, and there is also the need for strong and elaboratestirring equipment since the viscosity of the polymerization mixture canbecome very high. In the absence of added diluent, the high cementviscosity and exotherm effects can make temperature control verydifficult. Consequently, local hot spots may occur, resulting indegradation, gelation, and/or discoloration of the polymer product. Inthe extreme case, uncontrolled acceleration of the polymerization ratecan lead to disastrous “runaway” reactions. To facilitate thetemperature control during bulk polymerization, it is desirable that acatalyst gives a reaction rate that is sufficiently fast for economicalreasons but is slow enough to allow for the removal of the heat from thepolymerization exotherm in order to ensure the process safety.

Lanthanide-based catalyst systems that comprise a lanthanide-containingcompound, an alkylating agent, and a halogen source are known to beuseful for producing conjugated diene polymers having highcis-1,4-linkage contents. Nevertheless, when applied to bulkpolymerization of conjugated dienes, lanthanide-based catalyst systems,especially those comprising an aluminoxane compound as a catalystcomponent, often give excessively fast polymerization rates, which makesit very difficult to control the temperature and compromises the processsafety. Therefore, it is desirable to develop a method of moderating thebulk polymerization of conjugated dienes catalyzed by lanthanide-basedcatalysts.

SUMMARY OF THE INVENTION

One or more embodiments of the present invention provide a method forproducing a polydiene, the method comprising of combining a lanthanidecompound, an alkylating agent, a halogen source, and optionallyconjugated diene monomer to form an active preformed catalyst;independent of step (i), introducing an amine with conjugated dienemonomer to be polymerized; independent of step (i), introducing theactive preformed catalyst to the conjugated diene monomer to bepolymerized to form an active polymerization mixture, where the activepolymerization mixture includes less than 10% by weight, based on thetotal weight of the active polymerization mixture, of a solvent; andallowing the monomer to be polymerized to polymerize in the presence ofthe amine.

Other embodiments of the present invention provide a method forproducing a polydiene, the method comprising of combining a lanthanidecompound, an alkylating agent, a halogen source, and optionallyconjugated diene monomer to form an active preformed catalyst;independent of step (i), introducing an amine with conjugated dienemonomer to be polymerized; independent of step (i), introducing theactive preformed catalyst to the conjugated diene monomer to bepolymerized to form an active polymerization mixture; and allowing themonomer to be polymerized to polymerize in the presence of the amine,where the lanthanide compound is a lanthanide carboxylate, lanthanideorganophosphate, lanthanide organophosphonate, lanthanideorganophosphinate, lanthanide carbamate, lanthanide dithiocarbamate,lanthanide xanthate, lanthanide β-diketonate, lanthanide alkoxide oraryloxide, or organolanthanide compound.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Embodiments of this invention are based, at least in part, on thediscovery of a process for producing high cis-1,4-polydienes thatincludes polymerizing conjugated dienes with a lanthanide-based catalystin the presence of an amine. While the prior art contemplates inclusionof amines into lanthanide-based catalyst systems employed in dienepolymerization, it has now been observed that the cis-1,4-linkagecontent of the polydienes can be unexpectedly increased by forming anactive catalyst in the substantial absence of amine and thensubsequently polymerizing monomer with the active catalyst in thepresence of an amine. These polymers are also advantageouslycharacterized by a narrow molecular weight distribution and a highpercentage of chain ends possessing a reactive end. Additionally, thepresence of an amine is particularly advantageous in bulk polymerizationsystems because it has been discovered that the presence of the aminemodulates the polymerization rate and thereby facilitates temperaturecontrol and reduces the risk of runaway reactions in bulkpolymerization.

Practice of the present invention is not necessarily limited by theselection of any particular lanthanide-based catalyst system. In one ormore embodiments, the catalyst systems employed include (a) alanthanide-containing compound, (b) an alkylating agent, and (c) ahalogen source. In other embodiments, a compound containing anon-coordinating anion or a non-coordinating anion precursor can beemployed in lieu of a halogen source. In these or other embodiments,other organometallic compounds, Lewis bases, and/or catalyst modifierscan be employed in addition to the ingredients or components set forthabove. For example, in one embodiment, a nickel-containing compound canbe employed as a molecular weight regulator as disclosed in U.S. Pat.No. 6,699,813, which is incorporated herein by reference.

Examples of conjugated diene monomer include 1,3-butadiene, isoprene,1,3-pentadiene, 1,3-hexadiene, 2,3-dimethyl-1,3-butadiene,2-ethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene,4-methyl-1,3-pentadiene, and 2,4-hexadiene. Mixtures of two or moreconjugated dienes may also be utilized in copolymerization.

As mentioned above, the catalyst systems employed in the presentinvention includes a lanthanide-containing compound.Lanthanide-containing compounds useful in the present invention arethose compounds that include at least one atom of lanthanum, neodymium,cerium, praseodymium, promethium, samarium, europium, gadolinium,terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, anddidymium. In one embodiment, these compounds can include neodymium,lanthanum, samarium, or didymium. As used herein, the term “didymium”shall denote a commercial mixture of rare-earth elements obtained frommonazite sand. In addition, the lanthanide-containing compounds usefulin the present invention can be in the form of elemental lanthanide.

The lanthanide atom in the lanthanide-containing compounds can be invarious oxidation states including, but not limited to, the 0, +2, +3,and +4 oxidation states. In one embodiment, a trivalentlanthanide-containing compound, where the lanthanide atom is in the +3oxidation state, can be employed. Suitable lanthanide-containingcompounds include, but are not limited to, lanthanide carboxylates,lanthanide organophosphates, lanthanide organophosphonates, lanthanideorganophosphinates, lanthanide carbamates, lanthanide dithiocarbamates,lanthanide xanthates, lanthanide β-diketonates, lanthanide alkoxides oraryloxides, lanthanide halides, lanthanide pseudo-halides, lanthanideoxyhalides, and organolanthanide compounds.

In one or more embodiments, the lanthanide-containing compounds can besoluble in hydrocarbon solvents such as aromatic hydrocarbons, aliphatichydrocarbons, or cycloaliphatic hydrocarbons. Hydrocarbon-insolublelanthanide-containing compounds, however, may also be useful in thepresent invention, as they can be suspended in the polymerization mediumto form the catalytically active species.

For ease of illustration, further discussion of usefullanthanide-containing compounds will focus on neodymium compounds,although those skilled in the art will be able to select similarcompounds that are based upon other lanthanide metals.

Suitable neodymium carboxylates include, but are not limited to,neodymium formate, neodymium acetate, neodymium acrylate, neodymiummethacrylate, neodymium valerate, neodymium gluconate, neodymiumcitrate, neodymium fumarate, neodymium lactate, neodymium maleate,neodymium oxalate, neodymium 2-ethylhexanoate, neodymium neodecanoate(a.k.a., neodymium versatate), neodymium naphthenate, neodymiumstearate, neodymium oleate, neodymium benzoate, and neodymiumpicolinate.

Suitable neodymium organophosphates include, but are not limited to,neodymium dibutyl phosphate, neodymium dipentyl phosphate, neodymiumdihexyl phosphate, neodymium diheptyl phosphate, neodymium dioctylphosphate, neodymium bis(1-methylheptyl) phosphate, neodymiumbis(2-ethylhexyl) phosphate, neodymium didecyl phosphate, neodymiumdidodecyl phosphate, neodymium dioctadecyl phosphate, neodymium dioleylphosphate, neodymium diphenyl phosphate, neodymium bis(p-nonylphenyl)phosphate, neodymium butyl (2-ethylhexyl) phosphate, neodymium(1-methylheptyl) (2-ethylhexyl) phosphate, and neodymium (2-ethylhexyl)(p-nonylphenyl) phosphate.

Suitable neodymium organophosphonates include, but are not limited to,neodymium butyl phosphonate, neodymium pentyl phosphonate, neodymiumhexyl phosphonate, neodymium heptyl phosphonate, neodymium octylphosphonate, neodymium (1-methylheptyl) phosphonate, neodymium(2-ethylhexyl) phosphonate, neodymium decyl phosphonate, neodymiumdodecyl phosphonate, neodymium octadecyl phosphonate, neodymium oleylphosphonate, neodymium phenyl phosphonate, neodymium (p-nonylphenyl)phosphonate, neodymium butyl butylphosphonate, neodymium pentylpentylphosphonate, neodymium hexyl hexylphosphonate, neodymium heptylheptylphosphonate, neodymium octyl octylphosphonate, neodymium(1-methylheptyl) (1-methylheptyl)phosphonate, neodymium (2-ethylhexyl)(2-ethylhexyl)phosphonate, neodymium decyl decylphosphonate, neodymiumdodecyl dodecylphosphonate, neodymium octadecyl octadecylphosphonate,neodymium oleyl oleylphosphonate, neodymium phenyl phenylphosphonate,neodymium (p-nonylphenyl) (p-nonylphenyl) phosphonate, neodymium butyl(2-ethylhexyl)phosphonate, neodymium (2-ethylhexyl) butylphosphonate,neodymium (1-methylheptyl) (2-ethylhexyl)phosphonate, neodymium(2-ethylhexyl) (1-methylheptyl)phosphonate, neodymium (2-ethylhexyl)(p-nonylphenyl)phosphonate, and neodymium (p-nonylphenyl)(2-ethylhexyl)phosphonate.

Suitable neodymium organophosphinates include, but are not limited to,neodymium butylphosphinate, neodymium pentylphosphinate, neodymiumhexylphosphinate, neodymium heptylphosphinate, neodymiumoctylphosphinate, neodymium (1-methylheptyl)phosphinate, neodymium(2-ethylhexyl)phosphinate, neodymium decylphosphinate, neodymiumdodecylphosphinate, neodymium octadecylphosphinate, neodymiumoleylphosphinate, neodymium phenylphosphinate, neodymium(p-nonylphenyl)phosphinate, neodymium dibutylphosphinate, neodymiumdipentylphosphinate, neodymium dihexylphosphinate, neodymiumdiheptylphosphinate, neodymium dioctylphosphinate, neodymiumbis(1-methylheptyl)phosphinate, neodymium bis(2-ethylhexyl)phosphinate,neodymium didecylphosphinate, neodymium didodecylphosphinate, neodymiumdioctadecylphosphinate, neodymium dioleylphosphinate, neodymiumdiphenylphosphinate, neodymium bis(p-nonylphenyl) phosphinate, neodymiumbutyl (2-ethylhexyl)phosphinate, neodymium (1-methylheptyl)(2-ethylhexyl)phosphinate, and neodymium (2-ethylhexyl) (p-nonylphenyl)phosphinate.

Suitable neodymium carbamates include, but are not limited to, neodymiumdimethylcarbamate, neodymium diethylcarbamate, neodymiumdiisopropylcarbamate, neodymium dibutylcarbamate, and neodymiumdibenzylcarbamate.

Suitable neodymium dithiocarbamates include, but are not limited to,neodymium dimethyldithiocarbamate, neodymium diethyldithiocarbamate,neodymium diisopropyldithiocarbamate, neodymium dibutyldithiocarbamate,and neodymium dibenzyldithiocarbamate.

Suitable neodymium xanthates include, but are not limited to, neodymiummethylxanthate, neodymium ethylxanthate, neodymium isopropylxanthate,neodymium butylxanthate, and neodymium benzylxanthate.

Suitable neodymium β-diketonates include, but are not limited to,neodymium acetylacetonate, neodymium trifluoroacetylacetonate, neodymiumhexafluoroacetylacetonate, neodymium benzoylacetonate, and neodymium2,2,6,6-tetramethyl-3,5-heptanedionate.

Suitable neodymium alkoxides or aryloxides include, but are not limitedto, neodymium methoxide, neodymium ethoxide, neodymium isopropoxide,neodymium 2-ethylhexoxide, neodymium phenoxide, neodymiumnonylphenoxide, and neodymium naphthoxide.

Suitable neodymium halides include, but are not limited to, neodymiumfluoride, neodymium chloride, neodymium bromide, and neodymium iodide;suitable neodymium pseudo-halides include, but are not limited to,neodymium cyanide, neodymium cyanate, neodymium thiocyanate, neodymiumazide, and neodymium ferrocyanide; and suitable neodymium oxyhalidesinclude, but are not limited to, neodymium oxyfluoride, neodymiumoxychloride, and neodymium oxybromide. A Lewis base, such astetrahydrofuran (“THF”), may be employed as an aid for solubilizingthese classes of neodymium compounds in inert organic solvents. Wherelanthanide halides, lanthanide oxyhalides, or otherlanthanide-containing compounds containing a halogen atom are employed,the lanthanide-containing compound may also serve as all or part of thehalogen source in the above-mentioned catalyst system.

As used herein, the term organolanthanide compound refers to anylanthanide-containing compound containing at least one lanthanide-carbonbond. These compounds are predominantly, though not exclusively, thosecontaining cyclopentadienyl (“Cp”), substituted cyclopentadienyl, allyl,and substituted allyl ligands. Suitable organolanthanide compoundsinclude, but are not limited to, Cp₃Ln, Cp₂LnR, Cp₂LnCl, CpLnCl₂,CpLn(cyclooctatetraene), (C₅Me₅)₂LnR, LnR₃, Ln(allyl)₃, andLn(allyl)₂Cl, where Ln represents a lanthanide atom, and R represents ahydrocarbyl group. In one or more embodiments, hydrocarbyl groups usefulin the present invention may contain heteroatoms such as, for example,nitrogen, oxygen, boron, silicon, sulfur, and phosphorus atoms.

As mentioned above, the catalyst systems employed in the presentinvention can include an alkylating agent. In one or more embodiments,alkylating agents, which may also be referred to as hydrocarbylatingagents, include organometallic compounds that can transfer one or morehydrocarbyl groups to another metal. Typically, these agents includeorganometallic compounds of electropositive metals such as Groups 1, 2,and 3 metals (Groups IA, IIA, and IIIA metals). Alkylating agents usefulin the present invention include, but are not limited to, organoaluminumand organomagnesium compounds. As used herein, the term organoaluminumcompound refers to any aluminum compound containing at least onealuminum-carbon bond. In one or more embodiments, organoaluminumcompounds that are soluble in a hydrocarbon solvent can be employed. Asused herein, the term organomagnesium compound refers to any magnesiumcompound that contains at least one magnesium-carbon bond. In one ormore embodiments, organomagnesium compounds that are soluble in ahydrocarbon can be employed. As will be described in more detail below,several species of suitable alkylating agents can be in the form of ahalide. Where the alkylating agent includes a halogen atom, thealkylating agent may also serve as all or part of the halogen source inthe above-mentioned catalyst system.

In one or more embodiments, organoaluminum compounds that can beutilized include those represented by the general formulaAlR_(n)X_(3-n), where each R independently can be a monovalent organicgroup that is attached to the aluminum atom via a carbon atom, whereeach X independently can be a hydrogen atom, a halogen atom, acarboxylate group, an alkoxide group, or an aryloxide group, and where ncan be an integer in the range of from 1 to 3. Where the organoaluminumcompound includes a halogen atom, the organoaluminum compound can serveas both the alkylating agent and at least a portion of the halogensource in the catalyst system. In one or more embodiments, each Rindependently can be a hydrocarbyl group such as, for example, alkyl,cycloalkyl, substituted cycloalkyl, alkenyl, cycloalkenyl, substitutedcycloalkenyl, aryl, substituted aryl, aralkyl, alkaryl, allyl, andalkynyl groups, with each group containing in the range of from 1 carbonatom, or the appropriate minimum number of carbon atoms to form thegroup, up to about 20 carbon atoms. These hydrocarbyl groups may containheteroatoms including, but not limited to, nitrogen, oxygen, boron,silicon, sulfur, and phosphorus atoms.

Types of the organoaluminum compounds that are represented by thegeneral formula AlR_(n)X_(3-n) include, but are not limited to,trihydrocarbylaluminum, dihydrocarbylaluminum hydride,hydrocarbylaluminum dihydride, dihydrocarbylaluminum carboxylate,hydrocarbylaluminum bis(carboxylate), dihydrocarbylaluminum alkoxide,hydrocarbylaluminum dialkoxide, dihydrocarbylaluminum halide,hydrocarbylaluminum dihalide, dihydrocarbylaluminum aryloxide, andhydrocarbylaluminum diaryloxide compounds. In one embodiment, thealkylating agent can comprise trihydrocarbylaluminum,dihydrocarbylaluminum hydride, and/or hydrocarbylaluminum dihydridecompounds. In one embodiment, when the alkylating agent includes anorganoaluminum hydride compound, the above-mentioned halogen source canbe provided by a tin halide, as disclosed in U.S. Pat. No. 7,008,899,which is incorporated herein by reference in its entirety.

Suitable trihydrocarbylaluminum compounds include, but are not limitedto, trimethylaluminum, triethylaluminum, triisobutylaluminum,tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum,tri-t-butylaluminum, tri-n-pentylaluminum, trineopentylaluminum,tri-n-hexylaluminum, tri-n-octylaluminum, tris(2-ethylhexyl)aluminum,tricyclohexylaluminum, tris(1-methylcyclopentyl)aluminum,triphenylaluminum, tri-p-tolylaluminum, tris(2,6-dimethylphenyl)aluminum, tribenzylaluminum, diethylphenylaluminum,diethyl-p-tolylaluminum, diethylbenzylaluminum, ethyldiphenylaluminum,ethyldi-p-tolylaluminum, and ethyldibenzylaluminum.

Suitable dihydrocarbylaluminum hydride compounds include, but are notlimited to, diethylaluminum hydride, di-n-propylaluminum hydride,diisopropylaluminum hydride, di-n-butylaluminum hydride,diisobutylaluminum hydride, di-n-octylaluminum hydride, diphenylaluminumhydride, di-p-tolylaluminum hydride, dibenzylaluminum hydride,phenylethylaluminum hydride, phenyl-n-propylaluminum hydride,phenylisopropylaluminum hydride, phenyl-n-butylaluminum hydride,phenylisobutylaluminum hydride, phenyl-n-octylaluminum hydride,p-tolylethylaluminum hydride, p-tolyl-n-propylaluminum hydride,p-tolylisopropylaluminum hydride, p-tolyl-n-butylaluminum hydride,p-tolylisobutylaluminum hydride, p-tolyl-n-octylaluminum hydride,benzylethylaluminum hydride, benzyl-n-propylaluminum hydride,benzylisopropylaluminum hydride, benzyl-n-butylaluminum hydride,benzylisobutylaluminum hydride, and benzyl-n-octylaluminum hydride.

Suitable hydrocarbylaluminum dihydrides include, but are not limited to,ethylaluminum dihydride, n-propylaluminum dihydride, isopropylaluminumdihydride, n-butylaluminum dihydride, isobutylaluminum dihydride, andn-octylaluminum dihydride.

Suitable dihydrocarbylaluminum halide compounds include, but are notlimited to, diethylaluminum chloride, di-n-propylaluminum chloride,diisopropylaluminum chloride, di-n-butylaluminum chloride,diisobutylaluminum chloride, di-n-octylaluminum chloride,diphenylaluminum chloride, di-p-tolylaluminum chloride, dibenzylaluminumchloride, phenylethylaluminum chloride, phenyl-n-propylaluminumchloride, phenylisopropylaluminum chloride, phenyl-n-butylaluminumchloride, phenylisobutylaluminum chloride, phenyl-n-octylaluminumchloride, p-tolylethylaluminum chloride, p-tolyl-n-propylaluminumchloride, p-tolylisopropylaluminum chloride, p-tolyl-n-butylaluminumchloride, p-tolylisobutylaluminum chloride, p-tolyl-n-octylaluminumchloride, benzylethylaluminum chloride, benzyl-n-propylaluminumchloride, benzylisopropylaluminum chloride, benzyl-n-butylaluminumchloride, benzylisobutylaluminum chloride, and benzyl-n-octylaluminumchloride.

Suitable hydrocarbylaluminum dihalide compounds include, but are notlimited to, ethylaluminum dichloride, n-propylaluminum dichloride,isopropylaluminum dichloride, n-butylaluminum dichloride,isobutylaluminum dichloride, and n-octylaluminum dichloride.

Other organoaluminum compounds useful as alkylating agents that may berepresented by the general formula AlR_(n)X_(3-n) include, but are notlimited to, dimethylaluminum hexanoate, diethylaluminum octoate,diisobutylaluminum 2-ethylhexanoate, dimethylaluminum neodecanoate,diethylaluminum stearate, diisobutylaluminum oleate, methylaluminumbis(hexanoate), ethylaluminum bis(octoate), isobutylaluminumbis(2-ethylhexanoate), methylaluminum bis(neodecanoate), ethylaluminumbis(stearate), isobutylaluminum bis(oleate), dimethylaluminum methoxide,diethylaluminum methoxide, diisobutylaluminum methoxide,dimethylaluminum ethoxide, diethylaluminum ethoxide, diisobutylaluminumethoxide, dimethylaluminum phenoxide, diethylaluminum phenoxide,diisobutylaluminum phenoxide, methylaluminum dimethoxide, ethylaluminumdimethoxide, isobutylaluminum dimethoxide, methylaluminum diethoxide,ethylaluminum diethoxide, isobutylaluminum diethoxide, methylaluminumdiphenoxide, ethylaluminum diphenoxide, and isobutylaluminumdiphenoxide.

Another class of organoaluminum compounds suitable for use as analkylating agent in the present invention is aluminoxanes. Aluminoxanescan comprise oligomeric linear aluminoxanes, which can be represented bythe general formula:

and oligomeric cyclic aluminoxanes, which can be represented by thegeneral formula:

where x can be an integer in the range of from 1 to about 100, or about10 to about 50; y can be an integer in the range of from 2 to about 100,or about 3 to about 20; and where each R independently can be amonovalent organic group that is attached to the aluminum atom via acarbon atom. In one embodiment, each R independently can be ahydrocarbyl group including, but not limited to, alkyl, cycloalkyl,substituted cycloalkyl, alkenyl, cycloalkenyl, substituted cycloalkenyl,aryl, substituted aryl, aralkyl, alkaryl, allyl, and alkynyl groups,with each group containing in the range of from 1 carbon atom, or theappropriate minimum number of carbon atoms to form the group, up toabout 20 carbon atoms. These hydrocarbyl groups may also containheteroatoms including, but not limited to, nitrogen, oxygen, boron,silicon, sulfur, and phosphorus atoms. It should be noted that thenumber of mol of the aluminoxane as used in this application refers tothe number of mol of the aluminum atoms rather than the number of mol ofthe oligomeric aluminoxane molecules. This convention is commonlyemployed in the art of catalyst systems utilizing aluminoxanes.

Aluminoxanes can be prepared by reacting trihydrocarbylaluminumcompounds with water. This reaction can be preformed according to knownmethods, such as, for example, (1) a method in which thetrihydrocarbylaluminum compound is dissolved in an organic solvent andthen contacted with water, (2) a method in which thetrihydrocarbylaluminum compound is reacted with water of crystallizationcontained in, for example, metal salts, or water adsorbed in inorganicor organic compounds, or (3) a method in which thetrihydrocarbylaluminum compound is reacted with water in the presence ofthe monomer or monomer solution that is to be polymerized.

Suitable aluminoxane compounds include, but are not limited to,methylaluminoxane (“MAO”), modified methylaluminoxane (“MMAO”),ethylaluminoxane, n-propylaluminoxane, isopropylaluminoxane,butylaluminoxane, is obutylaluminoxane, n-pentylaluminoxane,neopentylaluminoxane, n-hexylaluminoxane, n-octylaluminoxane,2-ethylhexylaluminoxane, cyclohexylaluminoxane,1-methylcyclopentylaluminoxane, phenylaluminoxane, and2,6-dimethylphenylaluminoxane. Modified methylaluminoxane can be formedby substituting about 20 to 80 percent of the methyl groups ofmethylaluminoxane with C₂ to C₁₂ hydrocarbyl groups, preferably withisobutyl groups, by using techniques known to those skilled in the art.

Aluminoxanes can be used alone or in combination with otherorganoaluminum compounds. In one embodiment, methylaluminoxane and atleast one other organoaluminum compound (e.g., AlR_(n)X_(3-n)), such asdiisobutyl aluminum hydride, can be employed in combination. U.S.Publication No. 2008/0182954, which is incorporated herein by referencein its entirety, provides other examples where aluminoxanes andorganoaluminum compounds can be employed in combination.

As mentioned above, alkylating agents useful in the present inventioncan comprise organomagnesium compounds. In one or more embodiments,organomagnesium compounds that can be utilized include those representedby the general formula MgR₂, where each R independently can be amonovalent organic group that is attached to the magnesium atom via acarbon atom. In one or more embodiments, each R independently can be ahydrocarbyl group including, but not limited to, alkyl, cycloalkyl,substituted cycloalkyl, alkenyl, cycloalkenyl, substituted cycloalkenyl,aryl, allyl, substituted aryl, aralkyl, alkaryl, and alkynyl groups,with each group containing in the range of from 1 carbon atom, or theappropriate minimum number of carbon atoms to form the group, up toabout 20 carbon atoms. These hydrocarbyl groups may also containheteroatoms including, but not limited to, nitrogen, oxygen, silicon,sulfur, and phosphorus atoms.

Suitable organomagnesium compounds that may be represented by thegeneral formula MgR₂ include, but are not limited to, diethylmagnesium,di-n-propylmagnesium, diisopropylmagnesium, dibutylmagnesium,dihexylmagnesium, diphenylmagnesium, and dibenzylmagnesium.

Another class of organomagnesium compounds that can be utilized as analkylating agent may be represented by the general formula RMgX, where Rcan be a monovalent organic group that is attached to the magnesium atomvia a carbon atom, and X can be a hydrogen atom, a halogen atom, acarboxylate group, an alkoxide group, or an aryloxide group. Where theorganomagnesium compound includes a halogen atom, the organomagnesiumcompound can serve as both the alkylating agent and at least a portionof the halogen source in the catalyst systems. In one or moreembodiments, R can be a hydrocarbyl group including, but not limited to,alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, cycloalkenyl,substituted cycloalkenyl, aryl, allyl, substituted aryl, aralkyl,alkaryl, and alkynyl groups, with each group containing in the range offrom 1 carbon atom, or the appropriate minimum number of carbon atoms toform the group, up to about 20 carbon atoms. These hydrocarbyl groupsmay also contain heteroatoms including, but not limited to, nitrogen,oxygen, boron, silicon, sulfur, and phosphorus atoms. In one embodiment,X can be a carboxylate group, an alkoxide group, or an aryloxide group,with each group containing in the range of from 1 to about 20 carbonatoms.

Types of organomagnesium compounds that may be represented by thegeneral formula RMgX include, but are not limited to,hydrocarbylmagnesium hydride, hydrocarbylmagnesium halide,hydrocarbylmagnesium carboxylate, hydrocarbylmagnesium alkoxide, andhydrocarbylmagnesium aryloxide.

Suitable organomagnesium compounds that may be represented by thegeneral formula RMgX include, but are not limited to, methylmagnesiumhydride, ethylmagnesium hydride, butylmagnesium hydride, hexylmagnesiumhydride, phenylmagnesium hydride, benzylmagnesium hydride,methylmagnesium chloride, ethylmagnesium chloride, butylmagnesiumchloride, hexylmagnesium chloride, phenylmagnesium chloride,benzylmagnesium chloride, methylmagnesium bromide, ethylmagnesiumbromide, butylmagnesium bromide, hexylmagnesium bromide, phenylmagnesiumbromide, benzylmagnesium bromide, methylmagnesium hexanoate,ethylmagnesium hexanoate, butylmagnesium hexanoate, hexylmagnesiumhexanoate, phenylmagnesium hexanoate, benzylmagnesium hexanoate,methylmagnesium ethoxide, ethylmagnesium ethoxide, butylmagnesiumethoxide, hexylmagnesium ethoxide, phenylmagnesium ethoxide,benzylmagnesium ethoxide, methylmagnesium phenoxide, ethylmagnesiumphenoxide, butylmagnesium phenoxide, hexylmagnesium phenoxide,phenylmagnesium phenoxide, and benzylmagnesium phenoxide.

As mentioned above, the catalyst systems employed in the presentinvention can include a halogen source. As used herein, the term halogensource refers to any substance including at least one halogen atom. Inone or more embodiments, at least a portion of the halogen source can beprovided by either of the above-described lanthanide-containing compoundand/or the above-described alkylating agent, when those compoundscontain at least one halogen atom. In other words, thelanthanide-containing compound can serve as both thelanthanide-containing compound and at least a portion of the halogensource. Similarly, the alkylating agent can serve as both the alkylatingagent and at least a portion of the halogen source.

In another embodiment, at least a portion of the halogen source can bepresent in the catalyst systems in the form of a separate and distincthalogen-containing compound. Various compounds, or mixtures thereof,that contain one or more halogen atoms can be employed as the halogensource. Examples of halogen atoms include, but are not limited to,fluorine, chlorine, bromine, and iodine. A combination of two or morehalogen atoms can also be utilized. Halogen-containing compounds thatare soluble in a hydrocarbon solvent are suitable for use in the presentinvention. Hydrocarbon-insoluble halogen-containing compounds, however,can be suspended in a polymerization system to form the catalyticallyactive species, and are therefore also useful.

Useful types of halogen-containing compounds that can be employedinclude, but are not limited to, elemental halogens, mixed halogens,hydrogen halides, organic halides, inorganic halides, metallic halides,and organometallic halides.

Elemental halogens suitable for use in the present invention include,but are not limited to, fluorine, chlorine, bromine, and iodine. Somespecific examples of suitable mixed halogens include iodinemonochloride, iodine monobromide, iodine trichloride, and iodinepentafluoride.

Hydrogen halides include, but are not limited to, hydrogen fluoride,hydrogen chloride, hydrogen bromide, and hydrogen iodide.

Organic halides include, but are not limited to, t-butyl chloride,t-butyl bromide, allyl chloride, allyl bromide, benzyl chloride, benzylbromide, chloro-di-phenylmethane, bromo-di-phenylmethane,triphenylmethyl chloride, triphenylmethyl bromide, benzylidene chloride,benzylidene bromide (also called α,α-dibromotoluene or benzal bromide),methyltrichlorosilane, phenyltrichlorosilane, dimethyldichlorosilane,diphenyldichlorosilane, trimethylchlorosilane, benzoyl chloride, benzoylbromide, propionyl chloride, propionyl bromide, methyl chloroformate,methyl bromoformate, carbon tetrabromide (also calledtetrabromomethane), tribromomethane (also called bromoform),bromomethane, dibromomethane, 1-bromopropane, 2-bromopropane,1,3-dibromopropane, 2,2-dimethyl-1-bromopropane (also called neopentylbromide), formyl bromide, acetyl bromide, propionyl bromide, butyrylbromide, isobutyryl bromide, valeroyl bromide, isovaleryl bromide,hexanoyl bromide, benzoyl bromide, methyl bromoacetate, methyl2-bromopropionate, methyl 3-bromopropionate, methyl 2-bromobutyrate,methyl 2-bromohexanoate, methyl 4-bromocrotonate, methyl2-bromobenzoate, methyl 3-bromobenzoate, methyl 4-bromobenzoate,iodomethane, diiodomethane, triiodomethane (also called iodoform),tetraiodomethane, 1-iodopropane, 2-iodopropane, 1,3-diiodopropane,t-butyl iodide, 2,2-dimethyl-1-iodopropane (also called neopentyliodide), allyl iodide, iodobenzene, benzyl iodide, diphenylmethyliodide, triphenylmethyl iodide, benzylidene iodide (also called benzaliodide or α,α-diiodotoluene), trimethylsilyl iodide, triethylsilyliodide, triphenylsilyl iodide, dimethyldiiodosilane,diethyldiiodosilane, diphenyldiiodosilane, methyltriiodosilane,ethyltriiodosilane, phenyltriiodosilane, benzoyl iodide, propionyliodide, and methyl iodoformate.

Inorganic halides include, but are not limited to, phosphorustrichloride, phosphorus tribromide, phosphorus pentachloride, phosphorusoxychloride, phosphorus oxybromide, boron trifluoride, borontrichloride, boron tribromide, silicon tetrafluoride, silicontetrachloride, silicon tetrabromide, silicon tetraiodide, arsenictrichloride, arsenic tribromide, arsenic triiodide, seleniumtetrachloride, selenium tetrabromide, tellurium tetrachloride, telluriumtetrabromide, and tellurium tetraiodide.

Metallic halides include, but are not limited to, tin tetrachloride, tintetrabromide, aluminum trichloride, aluminum tribromide, antimonytrichloride, antimony pentachloride, antimony tribromide, aluminumtriiodide, aluminum trifluoride, gallium trichloride, galliumtribromide, gallium triiodide, gallium trifluoride, indium trichloride,indium tribromide, indium triiodide, indium trifluoride, titaniumtetrachloride, titanium tetrabromide, titanium tetraiodide, zincdichloride, zinc dibromide, zinc diiodide, and zinc difluoride.

Organometallic halides include, but are not limited to, dimethylaluminumchloride, diethylaluminum chloride, dimethylaluminum bromide,diethylaluminum bromide, dimethylaluminum fluoride, diethylaluminumfluoride, methylaluminum dichloride, ethylaluminum dichloride,methylaluminum dibromide, ethylaluminum dibromide, methylaluminumdifluoride, ethylaluminum difluoride, methylaluminum sesquichloride,ethylaluminum sesquichloride, isobutylaluminum sesquichloride,methylmagnesium chloride, methylmagnesium bromide, methylmagnesiumiodide, ethylmagnesium chloride, ethylmagnesium bromide, butylmagnesiumchloride, butylmagnesium bromide, phenylmagnesium chloride,phenylmagnesium bromide, benzylmagnesium chloride, trimethyltinchloride, trimethyltin bromide, triethyltin chloride, triethyltinbromide, di-t-butyltin dichloride, di-t-butyltin dibromide, dibutyltindichloride, dibutyltin dibromide, tributyltin chloride, and tributyltinbromide.

In one or more embodiments, the above-described catalyst systems cancomprise a compound containing a non-coordinating anion or anon-coordinating anion precursor. In one or more embodiments, a compoundcontaining a non-coordinating anion, or a non-coordinating anionprecursor can be employed in lieu of the above-described halogen source.A non-coordinating anion is a sterically bulky anion that does not formcoordinate bonds with, for example, the active center of a catalystsystem due to steric hindrance. Non-coordinating anions useful in thepresent invention include, but are not limited to, tetraarylborateanions and fluorinated tetraarylborate anions. Compounds containing anon-coordinating anion can also contain a counter cation, such as acarbonium, ammonium, or phosphonium cation. Exemplary counter cationsinclude, but are not limited to, triarylcarbonium cations andN,N-dialkylanilinium cations. Examples of compounds containing anon-coordinating anion and a counter cation include, but are not limitedto, triphenylcarbonium tetrakis(pentafluorophenyl)borate,N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate,triphenylcarbonium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, andN,N-dimethylanilinium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate.

A non-coordinating anion precursor can also be used in this embodiment.A non-coordinating anion precursor is a compound that is able to form anon-coordinating anion under reaction conditions. Usefulnon-coordinating anion precursors include, but are not limited to,triarylboron compounds, BR₃, where R is a strong electron-withdrawingaryl group, such as a pentafluorophenyl or3,5-bis(trifluoromethyl)phenyl group.

As discussed above, an active catalyst is formed when thelanthanide-containing compound, the alkylating agent, and the halogensource are introduced. According to this invention, this takes place inthe substantial absence of an amine. The resulting active catalyst iscapable of polymerizing conjugated diene monomer to form a highcis-1,4-polydiene. Without wishing to be bound by any particular theory,it is believed that the active catalyst includes a π-allyl complex as anactive intermediate that is capable of coordinating with monomer andinserting monomer into a covalent bond between an active lanthanidemetal center and a growing polymer chain.

Although one or more active catalyst species are believed to result fromthe combination of the catalyst ingredients, the degree of interactionor reaction between the various catalyst ingredients or components isnot known with any great degree of certainty. Therefore, the term activecatalyst or catalyst composition has been employed to encompass a simplemixture of the ingredients, a complex of the various ingredients that iscaused by physical or chemical forces of attraction, a chemical reactionproduct of the ingredients, or a combination of the foregoingingredients, so long as this mixture, complex, reaction product, orcombination is capable of polymerizing monomer as discussed above.

The foregoing lanthanide-based catalyst composition may have highcatalytic activity for polymerizing conjugated dienes intocis-1,4-polydienes over a wide range of catalyst concentrations andcatalyst ingredient ratios. Several factors may impact the optimumconcentration of any one of the catalyst ingredients. For example,because the catalyst ingredients may interact to form an active species,the optimum concentration for any one catalyst ingredient may bedependent upon the concentrations of the other catalyst ingredients.

In one or more embodiments, the molar ratio of the alkylating agent tothe lanthanide-containing compound (alkylating agent/Ln) can be variedfrom about 1:1 to about 1,000:1, in other embodiments from about 2:1 toabout 500:1, and in other embodiments from about 5:1 to about 200:1.

In those embodiments where both an aluminoxane and at least one otherorganoaluminum agent are employed as alkylating agents, the molar ratioof the aluminoxane to the lanthanide-containing compound(aluminoxane/Ln) can be varied from 5:1 to about 1,000:1, in otherembodiments from about 10:1 to about 700:1, and in other embodimentsfrom about 20:1 to about 500:1; and the molar ratio of the at least oneother organoaluminum compound to the lanthanide-containing compound(Al/Ln) can be varied from about 1:1 to about 200:1, in otherembodiments from about 2:1 to about 150:1, and in other embodiments fromabout 5:1 to about 100:1.

The molar ratio of the halogen-containing compound to thelanthanide-containing compound is best described in terms of the ratioof the mole of halogen atoms in the halogen source to the mole oflanthanide atoms in the lanthanide-containing compound (halogen/Ln). Inone or more embodiments, the halogen/Ln molar ratio can be varied fromabout 0.5:1 to about 20:1, in other embodiments from about 1:1 to about10:1, and in other embodiments from about 2:1 to about 6:1.

In yet another embodiment, the molar ratio of the non-coordinating anionor non-coordinating anion precursor to the lanthanide-containingcompound (An/Ln) may be from about 0.5:1 to about 20:1, in otherembodiments from about 0.75:1 to about 10:1, and in other embodimentsfrom about 1:1 to about 6:1.

The active catalyst can be formed by various methods.

In one or more embodiments, the active catalyst may be preformed byusing a preforming procedure. That is, the catalyst ingredients arepre-mixed outside the polymerization system either in the absence of anymonomer or in the presence of a small amount of at least one conjugateddiene monomer at an appropriate temperature, which may be from about−20° C. to about 80° C. The resulting catalyst composition may bereferred to as a preformed catalyst. The preformed catalyst may be aged,if desired, prior to being added to the monomer that is to bepolymerized. As used herein, reference to a small amount of monomerrefers to a catalyst loading of greater than 2 mmol, in otherembodiments greater than 3 mmol, and in other embodiments greater than 4mmol of lanthanide-containing compound per 100 g of monomer during thecatalyst formation. In particular embodiments, the preformed catalystmay be prepared by an in-line preforming procedure whereby the catalystingredients are introduced into a feed line wherein they are mixedeither in the absence of any monomer or in the presence of a smallamount of at least one conjugated diene monomer. The resulting preformedcatalyst can be either stored for future use or directly fed to themonomer that is to be polymerized.

In other embodiments, the active catalyst may be formed in situ byadding the catalyst ingredients, in either a stepwise or simultaneousmanner, to the monomer to be polymerized. In one embodiment, thealkylating agent can be added first, followed by thelanthanide-containing compound, and then followed by the halogen sourceor by the compound containing a non-coordinating anion or thenon-coordinating anion precursor. In one or more embodiments, two of thecatalyst ingredients can be pre-combined prior to addition to themonomer. For example, the lanthanide-containing compound and thealkylating agent can be pre-combined and added as a single stream to themonomer. Alternatively, the halogen source and the alkylating agent canbe pre-combined and added as a single stream to the monomer. An in situformation of the catalyst may be characterized by a catalyst loading ofless than 2 mmol, in other embodiments less than 1 mmol, in otherembodiments less than 0.2 mmol, in other embodiments less than 0.1 mmol,in other embodiments less than 0.05 mmol, and in other embodiments lessthan or equal to 0.006 mmol of lanthanide-containing compound per 100 gof monomer during the catalyst formation.

Regardless of the method employed to prepare the active catalyst, theactive catalyst is formed in the substantial absence of an amine. Asused herein, reference to a substantial absence refers to that amount ofamine or less that will not deleteriously impact the formation orperformance of the catalyst. In one or more embodiments, the activecatalyst is formed in the presence of less than 10 mole, in otherembodiments in the presence of less than 2 mole, and in otherembodiments in the presence of less than 1 mole of amine per mole oflanthanide metal in the lanthanide-containing compound. In otherembodiments, the catalyst is formed in the essential absence of anamine, which refers to a de minimis amount or less of amine. Inparticular embodiments, the active catalyst is formed in the completeabsence of amine.

After the active catalyst is prepared by either a preforming procedureor in situ, the polymerization of conjugated diene monomer is conductedin presence of the active catalyst and an amine. In one or moreembodiments, the amine is introduced directly and individually to themonomer solution (or bulk monomer) that is to be polymerized. In otherwords, prior to being introduced to the polymerization system, the amineis not complexed with the various catalyst ingredients.

In one or more embodiments, the amine may be present in the monomersolution (or bulk monomer) prior to the introduction of the preformedcatalyst. For example, the amine is introduced directly and individuallyto the monomer solution (or bulk monomer), and then the preformedcatalyst is introduced to the mixture of the monomer and amine. In theseembodiments, the introduction of the amine to the monomer solution (orbulk monomer) forms a monomer/amine blend that is devoid of activecatalyst prior to the introduction of the preformed catalyst.

In other embodiments, the amine and the preformed catalyst may be addedsimultaneously, yet separately and individually, to the monomer solution(or bulk monomer) that is to be polymerized.

In other embodiments, the amine is introduced to the preformed catalystbefore the preformed catalyst is introduced to the monomer solution (orbulk monomer). Therefore, in these embodiments, the amine and thepreformed catalyst are introduced to the monomer solution (or bulkmonomer) as a single stream. For example, where the preformed catalystis prepared by an in-line preforming procedure as described above, theamine can be added to the preformed catalyst in line after formation ofthe catalyst. In some embodiments, the stream including the amine andthe preformed catalyst, is introduced to the monomer solution (or bulkmonomer) within a relatively short time after the amine and thepreformed catalyst are brought into contact. In particular embodiments,the stream including the amine and the preformed catalyst is introducedto the monomer solution (or bulk monomer) within less than 1 minuteafter the amine and the preformed catalyst are brought into contact.

In other embodiments, the amine is introduced to the monomer solution(or bulk monomer) after introduction of the catalyst ingredients forforming the active catalyst or introduction of the preformed catalyst.In other words, the amine is introduced to the monomer solution (or bulkmonomer) that contains the active catalyst. As described above, theactive catalyst may be formed by a preforming procedure or in situ. Asthose skilled in the art appreciate, where the active catalyst ispresent in the monomer solution (or bulk monomer) prior to theintroduction of the amine, the active catalyst may be in the form ofpropagating oligomeric species at the time the amine is introduced. Inthis regard, those skilled in the art will appreciate that reference toactive catalyst may refer to low molecular weight living orpseudo-living oligomeric species. In one or more embodiments, the amineis introduced before 5%, in other embodiments before 3%, in otherembodiments before 1%, and in other embodiments before 0.5% of themonomer is polymerized.

In one or more embodiments, suitable amines include those compoundsrepresented by the formula NR₃, where each R is independently ahydrocarbyl group or substituted hydrocarbyl group, or where two or moreR groups combine to form a divalent or trivalent organic group. Thehydrocarbyl group may contain heteroatoms such as, but not limited to,nitrogen, oxygen, silicon, tin, sulfur, boron, and phosphorous atoms.Examples of hydrocarbyl groups or substituted hydrocarbyl groupsinclude, but are not limited to, alkyl, cycloalkyl, substitutedcycloalkyl, alkenyl, cycloalkenyl, aryl, substituted aryl groups, andheterocyclic groups. In certain embodiments, suitable amines includethose compounds where the nitrogen atom of the amine has three bondsconnected to two or three carbon atoms. Specifically contemplated arethose amines where the nitrogen is singly bonded to three carbon atoms(e.g. trihydrocarbylamines). Also specifically contemplated are thoseamines where the nitrogen is singly bonded to a carbon atom and doublybonded to a second carbon atom (e.g. aromatic amines such as pyridine).

Exemplary alkyl groups include methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, t-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl,n-heptyl, 2-ethylhexyl, n-octyl, n-nonyl, and n-decyl groups.

Exemplary cycloalkyl groups include cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, 2-methylcyclohexyl, 2-t-butylcyclohexyl and4-t-butylcyclohexyl groups.

Exemplary aryl groups include phenyl, substituted phenyl, biphenyl,substituted biphenyl, bicyclic aryl, substituted bicyclic aryl,polycyclic aryl, and substituted polycyclic aryl groups. Substitutedaryl groups include those where a hydrogen atom is replaced by amono-valent organic group such as a hydrocarbyl group.

Exemplary substituted phenyl groups include 2-methylphenyl,3-methylphenyl, 4-methylphenyl, 2,3-dimethylphenyl, 3,4-dimethylphenyl,2,5-dimethylphenyl, 2,6-dimethylphenyl, and 2,4,6-trimethylphenyl (alsocalled mesityl) groups.

Exemplary bicyclic or polycyclic aryl groups include 1-naphthyl,2-napthyl, 9-anthryl, 9-phenanthryl, 2-benzo[b]thienyl,3-benzo[b]thienyl, 2-naphtho[2,3-b]thienyl, 2-thianthrenyl,1-isobenzofuranyl, 2-xanthenyl, 2-phenoxathiinyl, 2-indolizinyl,N-methyl-2-indolyl, N-methyl-indazol-3-yl, N-methyl-8-purinyl,3-isoquinolyl, 2-quinolyl, 3-cinnolinyl, 2-pteridinyl,N-methyl-2-carbazolyl, N-methyl-β-carbolin-3-yl, 3-phenanthridinyl,2-acridinyl, 1-phthalazinyl, 1,8-naphthyridin-2-yl, 2-quinoxalinyl,2-quinazolinyl, 1,7-phenanthrolin-3-yl, 1-phenazinyl,N-methyl-2-phenothiazinyl, 2-phenarsazinyl, and N-methyl-2-phenoxazinylgroups.

Exemplary heterocyclic groups include 2-thienyl, 3-thienyl, 2-furyl,3-furyl, N-methyl-2-pyrrolyl, N-methyl-3-pyrrolyl,N-methyl-2-imidazolyl, 1-pyrazolyl, N-methyl-3-pyrazolyl,N-methyl-4-pyrazolyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, pyrazinyl,2-pyrimidinyl, 3-pyridazinyl, 3-isothiazolyl, 3-isoxazolyl, 3-furazanyl,2-triazinyl, morpholinyl, thiomorpholinyl, piperidinyl, piperazinyl,pyrrolidinyl, pyrrolinyl, imidazolidinyl, and imidazolinyl groups.

In one or more embodiments, the amines are tertiary amines. In one ormore embodiments, the tertiary amines may include one or more acyclicsubstituents. In other embodiments, the tertiary amines may include oneor more cyclic, non-aromatic substituents. In yet other embodiments, thetertiary amines may include one or more aromatic substituents. Inparticular embodiments, the tertiary amines are devoid of aromaticsubstituents bonded directly to the nitrogen atom of the tertiary amine.In one or more embodiments, the tertiary amines are cyclic non-aromaticamines, where the nitrogen atom of the tertiary amine is a member of anon-aromatic ring. In other embodiments, the tertiary amines arearomatic amines, where the nitrogen atom of the tertiary amine is amember of an aromatic ring. In one or more embodiments, the tertiaryamines are monodentate compounds, which refers to the presence of onlyone lone pair of electrons that are capable of binding or coordinatingto the lanthanide metal of the lanthanide-containing compound.

Specific examples of tertiary amines that include acyclic substituentsinclude trimethylamine, triethylamine, tri-n-propylamine,triisopropylamine, tri-n-butylamine, triisobutylamine,tri-sec-butylamine, tripentylamine, triisopentylamine, tri-n-hexylamine,trioctylamine, trioctylamine, tricetylamine, tridodecylamine,triheptylamine, tri-iso-heptylamine, trinonylamine,N-methyl-N,N-dioctylamine, N,N-dimethyl-N-ethylamine,N-methyl-N-ethyl-N-propylamine, N,N-dimethyl-N-hexylamine,tri-isoamylamine, and triamylamine.

Specific examples of tertiary amines that include cyclic, non-aromaticsubstituents include tricyclopentylamine, tricyclohexylamine, andtricyclooctylamine.

Specific examples of tertiary amines that include an aromaticsubstituent include N,N-dimethyl-1-naphthylamine, N,N-dimethylaniline,N,N-diethylaniline, N,N-dimethylbenzylamine, and tribenzylamine.

Specific examples of cyclic, non-aromatic amines includeN-methylpyrrolidine, 1,2-dimethylpyrrolidine, 1,3-dimethylpyrrolidine,1,2,5-trimethylpyrrolidine, 2-methyl-2-pyrazoline, 1-methyl-2H-pyrrole,2H-pyrrole, 1-methylpyrrole, 2,4-dimethyl-1-methyl pyrrole,2,5-dimethyl-1-methyl pyrrole, N-methylpyrrole, 1,2,5-trimethylpyrrole,3-pyrroline, 2-pyrroline, 2-methyl-1-pyrroline, 2-imidazoline,N-ethylpiperidine, 1-ethylpiperidine, N-cyclohexyl-N,N-dimethylamine,quinuclidine, 3-(biphenyl-4-yl)quinuclidine, and 1-methyl-carbozole.

Specific examples of aromatic amines include pyridine, methylpyridine,2,6-dimethylpyridine, 2-methylpyridine, 3-methylpyridine,4-methylpyridine, dimethylpyridine, trimethylpyridine, ethylpyridine,2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2,4-diethylpyridine,2,6-diethylpyridine, 3,4-diethylpyridine, 2,3-, imethylpyridine,2,4-dimethylpyridine, 2,5-dimethylpyridine, 3,4-dimethylpyridine,3,5-dimethylpyridine, triethylpyridine, 1,4,5-triethylpyridine,2,4,5-triethylpyridine, 2,3,4-trimethylpyridine,2,3,5-trimethylpyridine, 2,3,6-trimethylpyridine,2,4,6-trimethylpyridine, propylpyridine, 3-methyl-4-propyl-pyridine,butylpyridine, 4-(1-butylpentyl)pyridine, 4-tert-butylpyridine,phenylpyridine, 3-methyl-2-phenylpyridine, diphenylpyridine,2-phenylpyridine, benzylpyridine, 4-pyrrolidinopyridine,1-methyl-4-phenylpyridine, 2-(1-ethylpropyl)pyridine,2,6-dimethyl-4-ethylpyridine, 3-ethyl-4-methylpyridine,3,5-dimethyl-2-ethylpyridine, 2,3,4,5-tetramethylpyridine, pyrazine,pyridazine, pyrimidine, 4-methylpyrimidine, 1,2,3-triazole,1,3,5-triazine, quinoline, 2-ethylquinoline, 3-ethylquinoline,4-ethylquinoline, 2-methylquinoline, 3-methylquinoline,4-methylquinoline, 5-methylquinoline, 6-methylquinoline,8-methylquinoline, 2,4-dimethylquinoline, 4,6-dimethylquinoline,4,7-dimethylquinoline, 5,8-dimethylquinoline, 6,8-dimethylquinoline,2,4,7-trimethylquinoline, isoquinoline, 4-ethyl-isoquinoline,1-ethylisoquinoline, 3-ethylisoquinoline, 4-methyl-2-phenylimidazole,2-(4-methylphenyl)indolizine, indolizine, quinoxaline,2-amino-8-methyl-quinoxaline, 1-methylindole, 1,8-naphthyridine,cinnoline, quinazoline, pteridine, acridine, phenazine,1-methylpyrazole, 1,3-dimethylpyrazole, 1,3,4-trimethylpyrazole,3,5-dimethyl-1-phenylpyrazole, and 3,4-dimethyl-1-phenylpyrazole.

In one or more embodiments, the amount of the amine introduced to themonomer solution (or bulk monomer) to be polymerized, and therefore ispresent during polymerization, may be represented by the molar ratio ofthe amine to the lanthanide-containing compound (amine/Ln). In one ormore embodiments, the amine/Ln molar ratio is at least 10:1, in otherembodiments at least 20:1, in other embodiments at least 30:1, and inother embodiments at least 40:1. In these or other embodiments, theamine/Ln molar ratio is less than 80:1, in other embodiments less than70:1, and in other embodiments less than 60:1. In one or moreembodiments, the amine/Ln molar ratio is from about 10:1 to about 80:1,in other embodiments from about 20:1 to about 70:1, and in otherembodiments from about 30:1 to about 60:1.

In other embodiments, the amount of the amine introduced to the monomersolution (or bulk monomer) to be polymerized may be expressed withrespect to the amount of the monomer. In one or more embodiments, theamount of the amine introduced is at least 0.01 mmol, in otherembodiments at least 0.1 mmol, in other embodiments at least 0.2 mmol,in other embodiments at least 0.3 mmol, and in other embodiments atleast 0.4 mmol per 100 g of monomer. In these or other embodiments, theamount of the amine introduced is less than 160 mmol, in otherembodiments less than 140 mmol, in other embodiments less than 120 mmol,in other embodiments less than 100 mmol, in other embodiments less than50 mmol, in other embodiments less than 10 mmol, and in otherembodiments less than 1.0 mmol per 100 g of monomer.

In one or more embodiments, a solvent may be employed as a carrier toeither dissolve or suspend the catalyst, catalyst ingredients, and/oramine in order to facilitate the delivery of the same to thepolymerization system. In other embodiments, monomer can be used as thecarrier. In yet other embodiments, the catalyst ingredients or amine canbe introduced in their neat state without any solvent.

In one or more embodiments, suitable solvents include those organiccompounds that will not undergo polymerization or incorporation intopropagating polymer chains during the polymerization of monomer in thepresence of the catalyst. In one or more embodiments, these organicspecies are liquid at ambient temperature and pressure. In one or moreembodiments, these organic solvents are inert to the catalyst. Exemplaryorganic solvents include hydrocarbons with a low or relatively lowboiling point such as aromatic hydrocarbons, aliphatic hydrocarbons, andcycloaliphatic hydrocarbons. Non-limiting examples of aromatichydrocarbons include benzene, toluene, xylenes, ethylbenzene,diethylbenzene, and mesitylene. Non-limiting examples of aliphatichydrocarbons include n-pentane, n-hexane, n-heptane, n-octane, n-nonane,n-decane, isopentane, isohexanes, isopentanes, isooctanes,2,2-dimethylbutane, petroleum ether, kerosene, and petroleum spirits.And, non-limiting examples of cycloaliphatic hydrocarbons includecyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane.Mixtures of the above hydrocarbons may also be used. As is known in theart, aliphatic and cycloaliphatic hydrocarbons may be desirably employedfor environmental reasons. The low-boiling hydrocarbon solvents aretypically separated from the polymer upon completion of thepolymerization.

Other examples of organic solvents include high-boiling hydrocarbons ofhigh molecular weights, including hydrocarbon oils that are commonlyused to oil-extend polymers. Examples of these oils include paraffinicoils, aromatic oils, naphthenic oils, vegetable oils other than castoroils, and low PCA oils including MES, TDAE, SRAE, heavy naphthenic oils.Since these hydrocarbons are non-volatile, they typically do not requireseparation and remain incorporated in the polymer.

The production of polymer according to this invention can beaccomplished by polymerizing conjugated diene monomer in the presence ofa catalytically effective amount of the active catalyst. Theintroduction of the catalyst, the conjugated diene monomer, the amine,and any solvent, if employed, forms a polymerization mixture in which areactive polymer is formed. The amount of the catalyst to be employedmay depend on the interplay of various factors such as the type ofcatalyst employed, the purity of the ingredients, the polymerizationtemperature, the polymerization rate and conversion desired, themolecular weight desired, and many other factors. Accordingly, aspecific catalyst amount cannot be definitively set forth except to saythat catalytically effective amounts of the catalyst may be used.

In one or more embodiments, the amount of the lanthanide-containingcompound used can be varied from about 0.001 to about 2 mmol, in otherembodiments from about 0.005 to about 1 mmol, and in still otherembodiments from about 0.01 to about 0.2 mmol per 100 gram of monomer.

In one or more embodiments, the polymerization of conjugated dienemonomer according to this invention may be carried out in apolymerization system that includes a substantial amount of solvent. Inone embodiment, a solution polymerization system may be employed inwhich both the monomer to be polymerized and the polymer formed aresoluble in the solvent. In another embodiment, a precipitationpolymerization system may be employed by choosing a solvent in which thepolymer formed is insoluble. In both cases, an amount of solvent inaddition to the amount of solvent that may be used in preparing thecatalyst is usually added to the polymerization system. The additionalsolvent may be the same as or different from the solvent used inpreparing the catalyst. Exemplary solvents have been set forth above. Inone or more embodiments, the solvent content of the polymerizationmixture may be more than 20% by weight, in other embodiments more than50% by weight, and in still other embodiments more than 80% by weightbased on the total weight of the polymerization mixture.

In other embodiments, the polymerization may be conducted in a bulkpolymerization system that includes substantially no solvent or aminimal amount of solvent. Those skilled in the art will appreciate thebenefits of bulk polymerization processes (i.e., processes where monomeracts as the solvent), and therefore the polymerization system includesless solvent than will deleteriously impact the benefits sought byconducting bulk polymerization. In one or more embodiments, the solventcontent of the polymerization mixture may be less than about 20% byweight, in other embodiments less than about 10% by weight, and in stillother embodiments less than about 5% by weight based on the total weightof the polymerization mixture. In another embodiment, the polymerizationmixture contains no solvents other than those that are inherent to theraw materials employed. In still another embodiment, the polymerizationmixture is substantially devoid of solvent, which refers to the absenceof that amount of solvent that would otherwise have an appreciableimpact on the polymerization process. Polymerization systems that aresubstantially devoid of solvent may be referred to as includingsubstantially no solvent. In particular embodiments, the polymerizationmixture is devoid of solvent.

The polymerization may be conducted in any conventional polymerizationvessels known in the art. In one or more embodiments, solutionpolymerization can be conducted in a conventional stirred-tank reactor.In other embodiments, bulk polymerization can be conducted in aconventional stirred-tank reactor, especially if the monomer conversionis less than about 60%. In still other embodiments, especially where themonomer conversion in a bulk polymerization process is higher than about60%, which typically results in a highly viscous cement, the bulkpolymerization may be conducted in an elongated reactor in which theviscous cement under polymerization is driven to move by piston, orsubstantially by piston. For example, extruders in which the cement ispushed along by a self-cleaning single-screw or double-screw agitatorare suitable for this purpose. Examples of useful bulk polymerizationprocesses are disclosed in U.S. Pat. No. 7,351,776, which isincorporated herein by reference.

In one or more embodiments, all of the ingredients used for thepolymerization can be combined within a single vessel (e.g., aconventional stirred-tank reactor), and all steps of the polymerizationprocess can be conducted within this vessel. In other embodiments, twoor more of the ingredients can be pre-combined in one vessel and thentransferred to another vessel where the polymerization of monomer (or atleast a major portion thereof) may be conducted.

The polymerization can be carried out as a batch process, a continuousprocess, or a semi-continuous process. In the semi-continuous process,the monomer is intermittently charged as needed to replace that monomeralready polymerized. In one or more embodiments, the conditions underwhich the polymerization proceeds may be controlled to maintain thetemperature of the polymerization mixture within a range from about −10°C. to about 200° C., in other embodiments from about 0° C. to about 150°C., and in other embodiments from about 20° C. to about 100° C. Inparticular embodiments, the polymerization takes place, or at least aportion of the polymerization takes place, at a temperature of at least30° C., in other embodiments at least 40° C., and in other embodimentsat least 50° C.

In one or more embodiments, the heat of polymerization may be removed byexternal cooling by a thermally controlled reactor jacket, internalcooling by evaporation and condensation of the monomer through the useof a reflux condenser connected to the reactor, or a combination of thetwo methods. Also, the polymerization conditions may be controlled toconduct the polymerization under a pressure of from about 0.1 atmosphereto about 50 atmospheres, in other embodiments from about 0.5 atmosphereto about 20 atmosphere, and in other embodiments from about 1 atmosphereto about 10 atmospheres. In one or more embodiments, the pressures atwhich the polymerization may be carried out include those that ensurethat the majority of the monomer is in the liquid phase. In these orother embodiments, the polymerization mixture may be maintained underanaerobic conditions.

In particular embodiments, the rate of polymerization is controlled byusing a variety of techniques including the use of an amine. Forexample, in one or more embodiments, the polymerization rate may bemaintained at a conversion rate of less than 4%, in other embodimentsless than 3%, and in other embodiments less than 2% conversion ofmonomer per minute. In particular embodiments, the polymerization ratemay be maintained at a conversion rate of greater than 0.3%, in otherembodiments greater than 0.5%, in other embodiments greater than 0.8%,in other embodiments greater than 1.0%, and in other embodiments greaterthan 1.2% conversion of monomer per minute.

Some or all of the polymer chains of the resulting reactive polymer maypossess reactive ends before the polymerization mixture is quenched. Thereactive polymer prepared according to this invention may be referred toas a pseudo-living polymer. In one or more embodiments, a polymerizationmixture including the reactive polymer may be referred to as an activepolymerization mixture. The percentage of polymer chains possessing areactive end depends on various factors such as the type of catalyst,the type of monomer, the purity of the ingredients, the polymerizationtemperature, the monomer conversion, and many other factors. In one ormore embodiments, at least about 90% of the polymer chains possess areactive end, in other embodiments at least about 95% of the polymerchains possess a reactive end, in other embodiments at least about 97%of the polymer chains possess a reactive end, and in still otherembodiments at least about 98% of the polymer chains possess a reactiveend.

Because the polydienes produced by the polymerization process of thisinvention may possess pseudo-living characteristics, a functionalizingagent may optionally be introduced into the polymerization mixture toreact with any reactive polymer chains so as to give a functionalizedpolymer. In one or more embodiments, the functionalizing agent isintroduced prior to contacting the polymerization mixture with aquenching agent. In other embodiments, the functionalizing may beintroduced after the polymerization mixture has been partially quenchedwith a quenching agent.

In one or more embodiments, functionalizing agents include compounds orreagents that can react with a reactive polymer produced by thisinvention and thereby provide the polymer with a functional group thatis distinct from a propagating chain that has not been reacted with thefunctionalizing agent. The functional group may be reactive orinteractive with other polymer chains (propagating and/ornon-propagating) or with other constituents such as reinforcing fillers(e.g. carbon black) that may be combined with the polymer. In one ormore embodiments, the reaction between the functionalizing agent and thereactive polymer proceeds via an addition or substitution reaction.

Useful functionalizing agents may include compounds that simply providea functional group at the end of a polymer chain without joining two ormore polymer chains together, as well as compounds that can couple orjoin two or more polymer chains together via a functional linkage toform a single macromolecule. The latter type of functionalizing agentsmay also be referred to as coupling agents.

In one or more embodiments, functionalizing agents include compoundsthat will add or impart a heteroatom to the polymer chain. In particularembodiments, functionalizing agents include those compounds that willimpart a functional group to the polymer chain to form a functionalizedpolymer that reduces the 50° C. hysteresis loss of a carbon-black filledvulcanizates prepared from the functionalized polymer as compared tosimilar carbon-black filled vulcanizates prepared fromnon-functionalized polymer. In one or more embodiments, this reductionin hysteresis loss is at least 5%, in other embodiments at least 10%,and in other embodiments at least 15%.

In one or more embodiments, suitable functionalizing agents includethose compounds that contain groups that may react with pseudo-livingpolymers (e.g., those produced in accordance with this invention).Exemplary functionalizing agents include ketones, quinones, aldehydes,amides, esters, isocyanates, isothiocyanates, epoxides, imines,aminoketones, aminothioketones, and acid anhydrides. Examples of thesecompounds are disclosed in U.S. Pat. Nos. 4,906,706, 4,990,573,5,064,910, 5,567,784, 5,844,050, 6,838,526, 6,977,281, and 6,992,147;U.S. Pat. Publ. Nos. 2006/0004131 A1, 2006/0025539 A1, 2006/0030677 A1,and 2004/0147694 A1; Japanese Patent Application Nos. 05-051406A,05-059103A, 10-306113A, and 11-035633A; which are incorporated herein byreference. Other examples of functionalizing agents include azinecompounds as described in U.S. Pat. Publ. No. 2007/0149717,hydrobenzamide compounds as disclosed in U.S. Pat. Publ. No.2007/0276122, nitro compounds as disclosed in U.S. Pat. Publ. No.2008/0051552, and protected oxime compounds as disclosed in U.S. Pat.Publ. No. 2008/0146745, all of which are incorporated herein byreference.

In particular embodiments, the functionalizing agents employed may becoupling agents which include, but are not limited to, metal halidessuch as tin tetrachloride, metalloid halides such as silicontetrachloride, metal ester-carboxylate complexes such as dioctyltinbis(octylmaleate), alkoxysilanes such as tetraethyl orthosilicate, andalkoxystannanes such as tetraethoxytin. Coupling agents can be employedeither alone or in combination with other functionalizing agents. Thecombination of functionalizing agents may be used in any molar ratio.

The amount of functionalizing agent introduced to the polymerizationmixture may depend upon various factors including the type and amount ofcatalyst used to initiate the polymerization, the type offunctionalizing agent, the desired level of functionality and many otherfactors. In one or more embodiments, the amount of functionalizing agentmay be in a range of from about 1 to about 200 mole, in otherembodiments from about 5 to about 150 mole, and in other embodimentsfrom about 10 to about 100 mole per mole of the lanthanide-containingcompound.

Because reactive polymer chains may slowly self-terminate at hightemperatures, in one embodiment the functionalizing agent may be addedto the polymerization mixture once a peak polymerization temperature isobserved. In other embodiments, the functionalizing agent may be addedwithin about 25 to 35 minutes after the peak polymerization temperatureis reached.

In one or more embodiments, the functionalizing agent may be introducedto the polymerization mixture after a desired monomer conversion isachieved but before a quenching agent containing a protic hydrogen atomis added. In one or more embodiments, the functionalizing agent is addedto the polymerization mixture after a monomer conversion of at least 5%,in other embodiments at least 10%, in other embodiments at least 20%, inother embodiments at least 50%, and in other embodiments at least 80%.In these or other embodiments, the functionalizing agent is added to thepolymerization mixture prior to a monomer conversion of 90%, in otherembodiments prior to 70% monomer conversion, in other embodiments priorto 50% monomer conversion, in other embodiments prior to 20% monomerconversion, and in other embodiments prior to 15%. In one or moreembodiments, the functionalizing agent is added after complete, orsubstantially complete monomer conversion. In particular embodiments, afunctionalizing agent may be introduced to the polymerization mixtureimmediately prior to, together with, or after the introduction of aLewis base as disclosed in U.S. Pat. Publ. No. 2009/0043046, which isincorporated herein by reference.

In one or more embodiments, the functionalizing agent may be introducedto the polymerization mixture at a location (e.g., within a vessel)where the polymerization (or at least a portion thereof) has beenconducted. In other embodiments, the functionalizing agent may beintroduced to the polymerization mixture at a location that is distinctfrom where the polymerization (or at least a portion thereof) has takenplace. For example, the functionalizing agent may be introduced to thepolymerization mixture in downstream vessels including downstreamreactors or tanks, in-line reactors or mixers, extruders, ordevolatilizers.

Once a functionalizing agent has been introduced to the polymerizationmixture and/or a desired reaction time has been provided, a quenchingagent can be added to the polymerization mixture in order to inactivateany residual reactive polymer chains and the catalyst or catalystcomponents. The quenching agent may be a protic compound, whichincludes, but is not limited to, an alcohol, a carboxylic acid, aninorganic acid, water, or a mixture thereof. In particular embodiments,the quenching agent includes a polyhydroxy compound as disclosed in U.S.Pat. Publ. No. 2009/0043055, which is incorporated herein by reference.An antioxidant such as 2,6-di-t-butyl-4-methylphenol may be added alongwith, before, or after the addition of the quenching agent. The amountof the antioxidant employed may be in the range of about 0.2% to about1% by weight of the polymer product. The quenching agent and theantioxidant may be added as neat materials or, if necessary, dissolvedin a hydrocarbon solvent or conjugated diene monomer prior to beingadded to the polymerization mixture. Additionally, the polymer productcan be oil extended by adding an oil to the polymer, which may be in theform of a polymer cement or polymer dissolved or suspended in monomer.Practice of the present invention does not limit the amount of oil thatmay be added, and therefore conventional amounts may be added (e.g.,5-50 phr). Useful oils or extenders that may be employed include, butare not limited to, aromatic oils, paraffinic oils, naphthenic oils,vegetable oils other than castor oils, low PCA oils including MES, TDAE,and SRAE, and heavy naphthenic oils.

Once the polymerization mixture has been quenched, the variousconstituents of the polymerization mixture may be recovered. In one ormore embodiments, the unreacted monomer can be recovered from thepolymerization mixture. For example, the monomer can be distilled fromthe polymerization mixture by using techniques known in the art. In oneor more embodiments, a devolatilizer may be employed to remove themonomer from the polymerization mixture. Once the monomer has beenremoved from the polymerization mixture, the monomer may be purified,stored, and/or recycled back to the polymerization process.

The polymer product may be recovered from the polymerization mixture byusing techniques known in the art. In one or more embodiments,desolventization and drying techniques may be used. For instance, thepolymer can be recovered by passing the polymerization mixture through aheated screw apparatus, such as a desolventizing extruder, in which thevolatile substances are removed by evaporation at appropriatetemperatures (e.g., about 100° C. to about 170° C.) and underatmospheric or sub-atmospheric pressure. This treatment serves to removeunreacted monomer as well as any low-boiling solvent. Alternatively, thepolymer can also be recovered by subjecting the polymerization mixtureto steam desolventization, followed by drying the resulting polymercrumbs in a hot air tunnel. The polymer can also be recovered bydirectly drying the polymerization mixture on a drum dryer.

In one or more embodiments, the polymers prepared according to thisinvention may contain unsaturation. In these or other embodiments, thepolymers are vulcanizable. In one or more embodiments, the polymers canhave a glass transition temperature (T_(g)) that is less than 0° C., inother embodiments less than −20° C., and in other embodiments less than−30° C. In one embodiment, these polymers may exhibit a single glasstransition temperature. In particular embodiments, the polymers may behydrogenated or partially hydrogenated.

In one or more embodiments, the polymers of this invention may becis-1,4-polydienes having a cis-1,4-linkage content that is greater than97%, in other embodiments greater than 98%, in other embodiments greaterthan 98.5%, in other embodiments greater than 99.0%, in otherembodiments greater than 99.1% and in other embodiments greater than99.2%, where the percentages are based upon the number of diene merunits adopting the cis-1,4-linkage versus the total number of diene merunits. Also, these polymers may have a 1,2-linkage content that is lessthan about 2%, in other embodiments less than 1.5%, in other embodimentsless than 1%, and in other embodiments less than 0.5%, where thepercentages are based upon the number of diene mer units adopting the1,2-linkage versus the total number of diene mer units. The balance ofthe diene mer units may adopt the trans-1,4-linkage. The cis-1,4-, 1,2-,and trans-1,4-linkage contents can be determined by infraredspectroscopy.

In one or more embodiments, the number average molecular weight (M_(n))of these polymers may be from about 1,000 to about 1,000,000, in otherembodiments from about 5,000 to about 200,000, in other embodiments fromabout 25,000 to about 150,000, and in other embodiments from about50,000 to about 120,000, as determined by using gel permeationchromatography (GPC) calibrated with polystyrene standards andMark-Houwink constants for the polymer in question.

In one or more embodiments, the molecular weight distribution orpolydispersity (M_(w)/M_(n)) of these polymers may be less than 5.0, inother embodiments less than 3.0, in other embodiments less than 2.5, inother embodiments less than 2.2, in other embodiments less than 2.1, inother embodiments less than 2.0, in other embodiments less than 1.8, andin other embodiments less than 1.5.

The polymers of this invention are particularly useful in preparingrubber compositions that can be used to manufacture tire components.Rubber compounding techniques and the additives employed therein aregenerally disclosed in The Compounding and Vulcanization of Rubber, inRubber Technology (2^(nd) Ed. 1973).

The rubber compositions can be prepared by using the polymers of thisinvention alone or together with other elastomers (i.e., polymers thatcan be vulcanized to form compositions possessing rubbery or elastomericproperties). Other elastomers that may be used include natural andsynthetic rubbers. The synthetic rubbers typically derive from thepolymerization of conjugated diene monomers, the copolymerization ofconjugated diene monomers with other monomers such as vinyl-substitutedaromatic monomers, or the copolymerization of ethylene with one or moreα-olefins and optionally one or more diene monomers.

Exemplary elastomers include natural rubber, synthetic polyisoprene,polybutadiene, polyisobutylene-co-isoprene, neoprene,poly(ethylene-co-propylene), poly(styrene-co-butadiene),poly(styrene-co-isoprene), poly(styrene-co-isoprene-co-butadiene),poly(isoprene-co-butadiene), poly(ethylene-co-propylene-co-diene),polysulfide rubber, acrylic rubber, urethane rubber, silicone rubber,epichlorohydrin rubber, and mixtures thereof. These elastomers can havea myriad of macromolecular structures including linear, branched, andstar-shaped structures.

The rubber compositions may include fillers such as inorganic andorganic fillers. Examples of organic fillers include carbon black andstarch. Examples of inorganic fillers include silica, aluminumhydroxide, magnesium hydroxide, mica, talc (hydrated magnesiumsilicate), and clays (hydrated aluminum silicates). Carbon blacks andsilicas are the most common fillers used in manufacturing tires. Incertain embodiments, a mixture of different fillers may beadvantageously employed.

In one or more embodiments, carbon blacks include furnace blacks,channel blacks, and lamp blacks. More specific examples of carbon blacksinclude super abrasion furnace blacks, intermediate super abrasionfurnace blacks, high abrasion furnace blacks, fast extrusion furnaceblacks, fine furnace blacks, semi-reinforcing furnace blacks, mediumprocessing channel blacks, hard processing channel blacks, conductingchannel blacks, and acetylene blacks.

In particular embodiments, the carbon blacks may have a surface area(EMSA) of at least 20 m²/g and in other embodiments at least 35 m²/g;surface area values can be determined by ASTM D-1765 using thecetyltrimethylammonium bromide (CTAS) technique. The carbon blacks maybe in a pelletized form or an unpelletized flocculent form. Thepreferred form of carbon black may depend upon the type of mixingequipment used to mix the rubber compound.

The amount of carbon black employed in the rubber compositions can be upto about 50 parts by weight per 100 parts by weight of rubber (phr),with about 5 to about 40 phr being typical.

Some commercially available silicas which may be used include Hi-Sil™215, Hi-Sil™ 233, and Hi-Sil™ 190 (PPG Industries, Inc.; Pittsburgh,Pa.). Other suppliers of commercially available silica include GraceDavison (Baltimore, Md.), Degussa Corp. (Parsippany, N.J.), RhodiaSilica Systems (Cranbury, N.J.), and J.M. Huber Corp. (Edison, N.J.).

In one or more embodiments, silicas may be characterized by theirsurface areas, which give a measure of their reinforcing character. TheBrunauer, Emmet and Teller (“BET”) method (described in J. Am. Chem.Soc., vol. 60, p. 309 et seq.) is a recognized method for determiningthe surface area. The BET surface area of silica is generally less than450 m²/g. Useful ranges of surface area include from about 32 to about400 m²/g, about 100 to about 250 m²/g, and about 150 to about 220 m²/g.

The pH's of the silicas are generally from about 5 to about 7 orslightly over 7, or in other embodiments from about 5.5 to about 6.8.

In one or more embodiments, where silica is employed as a filler (aloneor in combination with other fillers), a coupling agent and/or ashielding agent may be added to the rubber compositions during mixing inorder to enhance the interaction of silica with the elastomers. Usefulcoupling agents and shielding agents are disclosed in U.S. Pat. Nos.3,842,111, 3,873,489, 3,978,103, 3,997,581, 4,002,594, 5,580,919,5,583,245, 5,663,396, 5,674,932, 5,684,171, 5,684,172 5,696,197,6,608,145, 6,667,362, 6,579,949, 6,590,017, 6,525,118, 6,342,552, and6,683,135, which are incorporated herein by reference.

The amount of silica employed in the rubber compositions can be fromabout 1 to about 100 phr or in other embodiments from about 5 to about80 phr. The useful upper range is limited by the high viscosity impartedby silicas. When silica is used together with carbon black, the amountof silica can be decreased to as low as about 1 phr; as the amount ofsilica is decreased, lesser amounts of coupling agents and shieldingagents can be employed. Generally, the amounts of coupling agents andshielding agents range from about 4% to about 20% based on the weight ofsilica used.

A multitude of rubber curing agents (also called vulcanizing agents) maybe employed, including sulfur or peroxide-based curing systems. Curingagents are described in Kirk-Othmer, ENCYCLOPEDIA OF CHEMICALTECHNOLOGY, VOL 20, pgs. 365-468, (3^(rd) Ed. 1982), particularlyVulcanization Agents and Auxiliary Materials, pgs. 390-402, and A. Y.Coran, Vulcanization, ENCYCLOPEDIA OF POLYMER SCIENCE AND ENGINEERING,(2^(nd) Ed. 1989), which are incorporated herein by reference.Vulcanizing agents may be used alone or in combination.

Other ingredients that are typically employed in rubber compounding mayalso be added to the rubber compositions. These include accelerators,accelerator activators, oils, plasticizer, waxes, scorch inhibitingagents, processing aids, zinc oxide, tackifying resins, reinforcingresins, fatty acids such as stearic acid, peptizers, and antidegradantssuch as antioxidants and antiozonants. In particular embodiments, theoils that are employed include those conventionally used as extenderoils, which are described above.

All ingredients of the rubber compositions can be mixed with standardmixing equipment such as Banbury or Brabender mixers, extruders,kneaders, and two-rolled mills. In one or more embodiments, theingredients are mixed in two or more stages. In the first stage (oftenreferred to as the masterbatch mixing stage), a so-called masterbatch,which typically includes the rubber component and filler, is prepared.To prevent premature vulcanization (also known as scorch), themasterbatch may exclude vulcanizing agents. The masterbatch may be mixedat a starting temperature of from about 25° C. to about 125° C. with adischarge temperature of about 135° C. to about 180° C. Once themasterbatch is prepared, the vulcanizing agents may be introduced andmixed into the masterbatch in a final mixing stage, which is typicallyconducted at relatively low temperatures so as to reduce the chances ofpremature vulcanization. Optionally, additional mixing stages, sometimescalled remills, can be employed between the masterbatch mixing stage andthe final mixing stage. One or more remill stages are often employedwhere the rubber composition includes silica as the filler. Variousingredients including the polymers of this invention can be added duringthese remills.

The mixing procedures and conditions particularly applicable tosilica-filled tire formulations are described in U.S. Pat. Nos.5,227,425, 5,719,207, and 5,717,022, as well as European Patent No.890,606, all of which are incorporated herein by reference. In oneembodiment, the initial masterbatch is prepared by including the polymerand silica in the substantial absence of coupling agents and shieldingagents.

The rubber compositions prepared from the polymers of this invention areparticularly useful for forming tire components such as treads,subtreads, sidewalls, body ply skims, bead filler, and the like. In oneor more embodiments, these tread or sidewall formulations may includefrom about 10% to about 100% by weight, in other embodiments from about35% to about 90% by weight, and in other embodiments from about 50% toabout 80% by weight of the polymer of this invention based on the totalweight of the rubber within the formulation.

Where the rubber compositions are employed in the manufacture of tires,these compositions can be processed into tire components according toordinary tire manufacturing techniques including standard rubbershaping, molding and curing techniques. Typically, vulcanization iseffected by heating the vulcanizable composition in a mold; e.g., it maybe heated to about 140° C. to about 180° C. Cured or crosslinked rubbercompositions may be referred to as vulcanizates, which generally containthree-dimensional polymeric networks that are thermoset. The otheringredients, such as fillers and processing aids, may be evenlydispersed throughout the crosslinked network. Pneumatic tires can bemade as discussed in U.S. Pat. Nos. 5,866,171, 5,876,527, 5,931,211, and5,971,046, which are incorporated herein by reference.

In order to demonstrate the practice of the present invention, thefollowing examples have been prepared and tested. The examples shouldnot, however, be viewed as limiting the scope of the invention. Theclaims will serve to define the invention.

EXAMPLES

In the following examples, the Mooney viscosities (ML₁₊₄) of the polymersamples were determined at 100° C. by using a Monsanto Mooney viscometerwith a large rotor, a one-minute warm-up time, and a four-minute runningtime. The number average (M_(n)) and weight average (M_(w)) molecularweights of the polymer samples were determined by gel permeationchromatography (GPC) and are reported in grams/mole. The GPC instrumentwas equipped with a differential refractive index (RI) detector and anultraviolet (UV) absorption detector. The GPC UV/RI ratio, which is theratio of the UV detector signal to the RI detector signal, was used tocalculate the % functionality of the polymer samples by referencing theGPC UV/RI ratio of the functionalized cis-1,4-polybutadiene to the UV/RIratio of a functionalized polybutadiene sample that is produced by usinganionic polymerization and has the same M_(n). The cis-1,4-linkage,trans-1,4-linkage, and 1,2-linkage contents of the polymer samples weredetermined by infrared spectroscopy.

Example 1

The polymerization reactor consisted of a one-gallon stainless cylinderequipped with a mechanical agitator (shaft and blades) capable of mixinghigh viscosity polymer cement. The top of the reactor was connected to areflux condenser system for conveying, condensing, and recycling the1,3-butadiene vapor developed inside the reactor throughout the durationof the polymerization. The reactor was also equipped with a coolingjacket chilled by cold water. The heat of polymerization was dissipatedpartly by internal cooling through the use of the reflux condensersystem, and partly by external cooling through heat transfer to thecooling jacket.

The reactor was thoroughly purged with a stream of dry nitrogen, whichwas then replaced with 1,3-butadiene vapor by charging 100 g of dry1,3-butadiene monomer to the reactor, heating the reactor to 65° C., andthen venting the 1,3-butadiene vapor from the top of the refluxcondenser system until no liquid 1,3-butadiene remained in the reactor.Cooling water was applied to the reflux condenser and the reactorjacket, and 1302 g of 1,3-butadiene monomer was charged into thereactor. After the monomer was thermostated at 32° C., thepolymerization was initiated by charging into the reactor a preformedcatalyst that had been prepared by mixing in the following order 6.5 gof 19.2 wt % 1,3-butadiene in hexane, 1.44 ml of 0.054 M neodymiumversatate in hexane, 5.20 ml of 1.5 M methylaluminoxane (MAO) intoluene, 2.81 ml of 1.0 M diisobutylaluminum hydride (DIBAH) in hexane,and 3.12 ml of 0.025 M tetrabromomethane (CBr₄) in hexane and allowingthe mixture to age for 15 minutes. After 1.7 minutes from thepolymerization commencement, the polymer was functionalized by charging10.0 ml of 1.0 M 4,4′-bis(diethylamino)benzophenone (DEAR). Afterstirring for 5 minutes, the polymerization mixture was terminated bydiluting the polymerization mixture with 6.0 ml isopropanol dissolved in1360 g of hexane and dropping the batch into 3 gallons of isopropanolcontaining 5 g of 2,6-di-tert-butyl-4-methylphenol. The coagulatedpolymer was drum dried.

The yield of the polymer was 164.3 g (12.6% conversion), and thepolymerization rate was calculated to be 7.4% conversion per minute. Theresulting polymer had the following properties: ML₁₊₄=15.2, Mn=127,000,Mw=179,000, Mw/Mn=1.4, a cis-1,4-linkage content=98.4%, atrans-1,4-linkage content=1.4%, a 1,2-linkage content=0.2%, and apercent functionality of 60%.

The results of this example are less than satisfactory. Namely, thepolymerization rate of 7.4% conversion per minute is relatively fast forbulk polymerization, suggesting the risk of a runaway reaction. Also,this fast rate increases the likelihood of gel formation within thereactor due to local hot spots. In addition, the cis-1,4-linkage contentand the percent functionality of the resulting polymer are lower thandesired.

Example 2

The same procedure as used in Example 1 was used except that 2.90 ml of1.0 M DIBAH in hexane was employed in preparing the catalyst, and that7.8 ml of 0.4 M pyridine in hexane was charged into the reactor aftercharging 1302 g of 1,3-butadiene monomer. After 19.5 minutes from thepolymerization commencement, the polymer was functionalized with DEABand terminated by diluting the polymerization mixture with 6.0 mlisopropanol dissolved in 1360 g of hexane and dropping the batch into 3gallons of isopropanol containing 5 g of2,6-di-tert-butyl-4-methylphenol. The coagulated polymer was drum dried

The yield of the polymer was 159.7 g (12.3% conversion), and thepolymerization rate was calculated to be 0.6% conversion per minute. Theresulting polymer had the following properties: ML₁₊₄=24.4, Mn=126,000,Mw=244,000, Mw/Mn=1.9, a 1,4-cis-1,4-linkage content=99.1%, atrans-1,4-linkage content=0.7%, a 1,2-linkage content=0.2%, and apercent functionality of 95%.

A comparison of these results with those of Example 1 shows thatpractice of the present invention leads to an advantageous balance ofresults and properties. Namely, the presence of pyridine during thepolymerization modulated the polymerization rate down to 0.6% conversionper minute, which suggests that the polymerization can take place atindustrially useful rates without significant risk of runawaypolymerization and reactor fouling. Moreover, the presence of pyridineduring the polymerization resulted in the formation of a polymer havinga higher cis-1,4-linkage content and a higher percent functionality ascompared to the polymer prepared in the absence of pyridine. Molecularweight distribution was only modestly impacted.

Example 3

The same procedure as used in Example 2 was generally followed exceptthat the active catalyst was generated in situ in the presence of themonomer to be polymerized as described in the following. The reactor wascharged with 1302 g of 1,3-butadiene monomer. After the monomer wasthermostated at 32° C., 1.44 ml of 0.054 M neodymium versatate in hexanefollowed by 5.20 ml of 1.5 M MAO in toluene was charged into thereactor. After ageing the solution while stirring for 5.0 minutes, 2.18ml of 1.0 M DIBAH in hexane was charged into the reactor. After 2.0minutes, 3.12 ml of 0.025 M CBr₄ in hexane was charged into the reactorto form the active catalyst. After 2.0 minutes from its commencement,7.8 ml of 0.4 M pyridine in hexane was added to the polymerizationsolution and a noticeable rate decrease was observed. After 28 minutesfrom the polymerization commencement, the polymer was functionalizedwith DEAB and terminated by diluting the polymerization mixture with 6.0ml isopropanol dissolved in 1360 g of hexane and dropping the batch into3 gallons of isopropanol containing 5 g of2,6-di-tert-butyl-4-methylphenol. The coagulated polymer was drum dried.

The yield of the polymer was 193.1 g (14.8% conversion), and thepolymerization rate was calculated to be 0.5% conversion per minute. Theresulting polymer had the following properties: ML₁₊₄=18.5, Mn=106,000,Mw=213,000, Mw/Mn=2.0, a cis-1,4-linkage content=98.8%, atrans-1,4-linkage content=0.9%, a 1,2-linkage content=0.3%, and apercent functionality of 80%.

A comparison of these results with those of Example 2 showspre-formation of the catalyst (i.e., Example 2) is advantageous over insitu formation of the catalyst (i.e., Example 3). Namely, the preformedcatalyst provides a faster polymerization rate than the catalyst formedin situ. In addition, the preformed catalyst yields a polymer having ahigher cis-1,4-linkage content and a higher percent functionality thancan be achieved by the catalyst formed in situ.

Example 4

The same procedure as used in Example 2 was used except that pyridinewas present during the catalyst preparation by adding pyridine after theaddition of neodymium versatate instead of adding pyridine directly andindividually to the butadiene monomer. Specifically, a preformedcatalyst was prepared by mixing in the following order 6.5 g of 19.2 wt% 1,3-butadiene in hexane, 1.44 ml of 0.054 M neodymium versatate inhexane, 7.8 ml of 0.4 M pyridine in hexane, 5.20 ml of 1.5 M MAO intoluene, 2.65 ml of 1.0 M DIBAH in hexane, and 3.12 ml of 0.025 M CBr₄in hexane and allowing the mixture to age for 15 minutes. After 30.0minutes from the addition of the preformed catalyst to the butadienemonomer, no polymerization had occurred.

In this example, the presence of pyridine during the catalystpreparation resulted in the formation of a precipitate in the catalystsolution that was believed to have prevented polymerization fromoccurring. In other words, this example shows the criticality of formingthe catalyst in the absence of an amine such as pyridine.

Example 5

The same procedure as used in Example 2 was used except that pyridinewas present during the catalyst preparation by adding pyridine after theaddition of MAO instead of adding pyridine directly and individually tothe butadiene monomer. Specifically, a preformed catalyst was preparedby mixing in the following order 6.5 g of 19.2 wt % 1,3-butadiene inhexane, 1.44 ml of 0.054 M neodymium versatate in hexane, 5.20 ml of 1.5M MAO in toluene, 7.8 ml of 0.4 M pyridine in hexane, 2.90 ml of 1.0 MDIBAH in hexane, and 3.12 ml of 0.025 M CBr₄ in hexane and allowing themixture to age for 15 minutes. After 30.0 minutes from the addition ofthe preformed catalyst to the butadiene monomer, no polymerization hadoccurred.

In this example, the presence of pyridine during the catalystpreparation resulted in the formation of a precipitate in the catalystsolution that was believed to have prevented polymerization fromoccurring. Again, this indicates the criticality of forming the catalystin the absence of an amine such as pyridine.

Example 6

The same procedure as used in Example 2 was used except that pyridinewas present during the catalyst preparation by adding pyridine after theaddition of DIBAH instead of adding pyridine directly and individuallyto the butadiene monomer. Specifically, a preformed catalyst that hadbeen prepared by mixing in the following order 6.5 g of 19.2 wt %1,3-butadiene in hexane, 1.44 ml of 0.054 M neodymium versatate inhexane, 5.20 ml of 1.5 M MAO in toluene, 2.90 ml of 1.0 M DIBAH inhexane, 7.8 ml of 0.4 M pyridine in hexane, and 3.12 ml of 0.025 M CBr₄in hexane and allowing the mixture to age for 15 minutes. After 30.0minutes from the addition of the preformed catalyst to the butadienemonomer, no polymerization had occurred.

In this example, the presence of pyridine during the catalystpreparation resulted in the formation of a precipitate in the catalystsolution which prevented polymerization from occurring. Again, thisindicates the criticality of forming the catalyst in the absence of anamine such as pyridine.

Example 7

A procedure similar to that used in Example 3 was used except that asolution of neodymium versatate, MAO, and DIBAH was added to a reactorcontaining pyridine, CBr₄, and butadiene monomer as described in thefollowing. A solution containing 6.5 g of 19.2 wt % 1,3-butadiene inhexane, 1.44 ml of 0.054 M neodymium versatate in hexane, 5.20 ml of 1.5M MAO in toluene, and 2.00 ml of 1.0 M DIBAH in hexane was prepared.After ageing for 2 minutes, the solution was transferred to thepolymerization reactor containing 7.8 ml of 0.4 M pyridine in hexane,3.12 ml of 0.025 M CBr₄ in hexane, and 1302 g of 1,3-butadiene monomer.After 10 minutes from the polymerization commencement, the polymer wasfunctionalized with DEAB and terminated by diluting the polymerizationmixture with 6.0 ml isopropanol dissolved in 1360 g of hexane anddropping the batch into 3 gallons of isopropanol containing 5 g of2,6-di-tert-butyl-4-methylphenol. The coagulated polymer was drum dried.

In this example, the polymerization fouled the reactor by producing aninsoluble polymer film (i.e. gel) within the reactor. The polymer wasisolated excluding the gel (i.e. the gel inside the reactor was notrecovered). The yield of the isolated polymer was 175.8 g (13.5%conversion), and the polymerization rate was calculated to be 1.4%conversion per minute. The isolated polymer had the followingproperties: ML₁₊₄=23.7, Mn=122,000, Mw=217,000, Mw/Mn=1.8, acis-1,4-linkage content=99.1%, a trans 1,4-linkage content=0.7%, a1,2-linkage content=0.2%, and a percent functionality of 93%.

This example shows that the presence of pyridine during catalystformation is detrimental to the polymerization since it results inreactor fouling. Again, this indicates the criticality of forming theactive catalyst in the absence of an amine such as pyridine.

Example 8

A procedure similar to that used in Example 3 was used except that asolution of MAO, DIBAH, and CBr₄ was added to a reactor containingpyridine, neodymium versatate, and butadiene monomer. Specifically, asolution containing 6.5 g of 19.2 wt % 1,3-butadiene in hexane, 5.20 mlof 1.5 M MAO in toluene, 2.73 ml of 1.0 M DIBAH in hexane, and 3.12 mlof 0.025 M CBr₄ was prepared. After being aged for 15 minutes, thesolution was transferred to the polymerization reactor containing 7.8 mlof 0.4 M pyridine in hexane, 1.44 ml of 0.054 M neodymium versatate inhexane, and 1302 g of 1,3-butadiene monomer. After 33 minutes from thepolymerization commencement, the polymer was functionalized with DEABand terminated by diluting the polymerization mixture with 6.0 mlisopropanol dissolved in 1360 g of hexane and dropping the batch into 3gallons of isopropanol containing 5 g of2,6-di-tert-butyl-4-methylphenol. The coagulated polymer was drum dried.

The yield of the polymer was 79.7 g (6.1% conversion), and thepolymerization rate was calculated to be 0.2% conversion per minute. Theresulting polymer had the following properties: ML₁₊₄=too low tomeasure, Mn=64,000, Mw=152,000, Mw/Mn=2.4, a cis 1,4-linkagecontent=98.8%, a trans 1,4-linkage content=0.9%, a 1,2-linkagecontent=0.3%, and a percent functionality of 76%.

This example shows that the presence of pyridine during catalystformation is detrimental to the polymerization. Namely, formation of thecatalyst in the presence of pyridine yielded a sluggish polymerization;the polymerization rate of 0.2% conversion per minute is notindustrially useful. Also, the polymerization fouled the reactor byforming some gel inside the reactor. Again, these results suggest thecriticality of forming the catalyst in the absence of an amine such aspyridine.

Example 9

The same procedure as used in Example 3 was used except that thepyridine was charged to the monomer first prior to adding the catalystingredients as described in the following. The reactor was charged with1302 g of 1,3-butadiene monomer. After the monomer was thermostated at32° C., 7.8 ml of 0.4 M pyridine in hexane, 1.44 ml of 0.054 M neodymiumversatate in hexane, and 5.20 ml of 1.5 M MAO in toluene were chargedinto the reactor, respectively. After ageing the solution while stirringfor 5.0 minutes, 2.73 ml of 1.0 M DIBAH in hexane was charged into thereactor. After 2.0 minutes, the polymerization was then initiated bycharging 3.12 ml of 0.025 M CBr₄ in hexane into the reactor. After 38minutes from the polymerization commencement, the polymer wasfunctionalized with DEAB and terminated by diluting the polymerizationmixture with 6.0 ml isopropanol dissolved in 1360 g of hexane anddropping the batch into 3 gallons of isopropanol containing 5 g of2,6-di-tert-butyl-4-methylphenol. The coagulated polymer was drum dried.

The yield of the polymer was 149.5 g (11.5% conversion), and thepolymerization rate was calculated to be 0.3% conversion per minute. Theresulting polymer had the following properties: ML₁₊₄=10.1, Mn=81,000,Mw=189,000, Mw/Mn=2.3, a cis 1,4-linkage content=98.6%, a trans1,4-linkage content=1.1%, a 1,2-linkage content=0.3%, and a percentfunctionality of 68%.

A comparison of these results with those of Example 3 shows that thepresence of pyridine during catalyst formation is detrimental to thepolymerization. Namely, formation of the catalyst in the presence ofpyridine yielded a sluggish polymerization; the polymerization rate of0.3% conversion per minute is not industrially useful. Also, thepolymerization fouled the reactor by forming some gel inside thereactor. In addition, the isolated polymer had a lower cis-1,4-linkagecontent, broader molecular weight distribution, and lower percentfunctionality as compared to the polymer prepared with the catalyst thatwas formed in the absence of pyridine. Again, these results suggest thecriticality of forming the catalyst in the absence of an amine such aspyridine.

Various modifications and alterations that do not depart from the scopeand spirit of this invention will become apparent to those skilled inthe art. This invention is not to be duly limited to the illustrativeembodiments set forth herein.

What is claimed is:
 1. A method for producing a polydiene, the methodcomprising: (i) combining a lanthanide compound, an alkylating agent, ahalogen source, and optionally conjugated diene monomer to form anactive preformed catalyst, where the lanthanide compound is not alanthanide halide, lanthanide pseudo-halide, or lanthanide oxyhalide;(ii) independent of step (i), introducing an amine with conjugated dienemonomer to be polymerized; (iii) independent of step (i), introducingthe active preformed catalyst to the conjugated diene monomer to bepolymerized to form an active polymerization mixture, where the activepolymerization mixture includes less than 10% by weight, based on thetotal weight of the active polymerization mixture, of a solvent; and(iv) allowing the conjugated diene monomer to be polymerized topolymerize in the presence of the amine; where the amine is introducedbefore 3% of the conjugated diene monomer that is to be polymerized ispolymerized.
 2. The method of claim 1, where the amine is defined by theformula NR₃, where each R, which may be the same or different, is ahydrocarbyl group or substituted hydrocarbyl group, or where two or moreR groups combine to form a divalent or trivalent organic group, andwhere the hydrocarbyl group, including any hydrocarbyl group forming asubstituted hydrocarbyl group, is selected from the group consisting ofalkyl, cycloalkyl, substituted cycloalkyl, alkenyl, cycloalkenyl, aryl,and substituted aryl groups.
 3. The method of claim 1, where the activepolymerization mixture includes less than 5% by weight, based on thetotal weight of the active polymerization mixture, of a solvent.
 4. Themethod of claim 1, where the active polymerization mixture issubstantially devoid of a solvent.
 5. The method of claim 1, where thelanthanide compound is a lanthanide carboxylate, lanthanideorganophosphate, lanthanide organophosphonate, lanthanideorganophosphinate, lanthanide carbamate, lanthanide dithiocarbamate,lanthanide xanthate, lanthanide β-diketonate, lanthanide alkoxide oraryloxide, or organolanthanide compound.
 6. The method of claim 1, wherethe ratio of the amine to the lanthanide-containing compound is at least20:1.
 7. The method of claim 1, where said step of introducing an amineto conjugated diene monomer that is to be polymerized forms anamine/monomer blend, and where said step of polymerizing the conjugateddiene monomer takes place within the amine/monomer blend.
 8. The methodof claim 1, where the amine and the preformed catalyst are introduced tothe conjugated diene monomer to be polymerized simultaneously.
 9. Themethod of claim 1, where the amine is a tertiary amine.
 10. The methodof claim 9, where the tertiary amine is selected from the groupconsisting of trimethylamine, triethylamine, tri-n-propylamine,triisopropylamine, tri-n-butylamine, triisobutylamine,tri-sec-butylamine, tripentylamine, triisopentylamine, tri-n-hexylamine,trioctylamine, tricetylamine, tridodecylamine, triheptylamine,tri-iso-heptylamine, trinonylamine, N-methyl-N,N-dioctylamine,N,N-dimethyl-N-ethylamine, N-methyl-N-ethyl-N-propylamine,N,N-dimethyl-Nhexylamine, tri-isoamylamine, and triamylamine.
 11. Themethod of claim 9, where the tertiary amine is selected from the groupconsisting of tricyclopentylamine, tricyclohexylamine, andtricyclooctylamine.
 12. The method of claim 9, where the tertiary amineis selected from the group consisting of N,N-dimethyl-1-naphthylamine,N,N-dimethylaniline, N,N-diethylaniline, N,N-dimethylbenzylamine, andtribenzylamine.
 13. The method of claim 9, where the tertiary amine isselected from the group consisting of N-methylpyrrolidine,1,2-dimethylpyrrolidine, 1,3-dimethylpyrrolidine,1,2,5-trimethylpyrrolidine, 2-methyl-2-pyrazoline, 1-methyl-2H-pyrrole,2H-pyrrole, 1-methylpyrrole, 2,4-dimethyl-1-methyl pyrrole,2,5-dimethyl-1-methyl pyrrole, N-methylpyrrole, 1,2,5-trimethylpyrrole,3-pyrroline, 2-pyrroline, 2-methyl-1-pyrroline, 2-imidazoline,N-ethylpiperidine, 1-ethylpiperidine, N-cyclohexyl-N,N-dimethylamine,quinuclidine, 3-(biphenyl-4-yl) quinuclidine, and 1-methyl-carbozole.14. The method of claim 9, where the tertiary amine includes pyridine,methylpyridine, 2,6-dimethylpyridine, 2-methylpyridine,3-methylpyridine, 4-methylpyridine, dimethylpyridine, trimethylpyridine,ethylpyridine, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine,2,4-diethylpyridine, 2,6-diethylpyridine, 3,4-diethylpyridine,2,3-,dimethylpyridine, 2,4-dimethylpyridine, 2,5-dimethylpyridine,3,4-dimethylpyridine, 3,5-dimethylpyridine, triethylpyridine,1,4,5-triethylpyridine, 2,4,5-triethylpyridine, 2,3,4-trimethylpyridine,2,3,5-trimethylpyridine, 2,3, 6-trimethylpyridine,2,4,6-trimethylpyridine, propylpyridine, 3-methyl-4-propyl-pyridine,butylpyridine, 4-(1-butylpentyl)pyridine, 4-tert-butylpyridine,phenylpyridine, 3-methyl-2-phenylpyridine, diphenylpyridine,2-phenylpyridine, benzylpyridine, 4-pyrrolidinopyridine,1-methyl-4-phenylpyridine, 2-(1-ethylpropyl)pyridine,2,6-dimethyl-4-ethylpyridine, 3-ethyl-4-methylpyridine,3,5-dimethyl-2-ethylpyridine, 2,3,4,5-tetramethylpyridine, pyrazine,pyridazine, pyrimidine, 4-methylpyrimidine, 1,2,3-triazole,1,3,5-triazine, quinoline, 2-ethylquinoline, 3-ethylquinoline,4-ethylquinoline, 2-methylquinoline, 3-methylquinoline,4-methylquinoline, 5-methylquinoline, 6-methylquinoline,8-methylquinoline, 2,4-dimethylquinoline, 4, 6-dimethylquinoline, 4,7-dimethylquinoline, 5,8-dimethylquinoline, 6,8-dimethylquinoline,2,4,7-trimethylquinoline, isoquinoline, 4-ethyl-isoquinoline,1-ethylisoquinoline, 3-ethylisoquinoline, 4-methyl-2-phenylimidazole,2-(4-methylphenyl)indolizine, indolizine, quinoxaline,2-amino-8-methyl-quinoxaline, 1-methylindole, 1,8-naphthyridine,cinnoline, quinazoline, pteridine, acridine, phenazine,1-methylpyrazole, 1,3-dimethylpyrazole, 1,3,4-trimethylpyrazole,3,5-dimethyl-1-phenylpyrazole, and 3,4-dimethyl-1-phenylpyrazole. 15.The method of claim 9, where the tertiary amine is pyridine.
 16. Amethod for producing a polydiene, the method comprising: (i) combining alanthanide compound, an alkylating agent, a halogen source, andoptionally conjugated diene monomer to form an active preformedcatalyst; (ii) independent of step (i), introducing an amine withconjugated diene monomer to be polymerized; (iii) independent of step(i), introducing the active preformed catalyst to the conjugated dienemonomer to be polymerized to form an active polymerization mixture; and(iv) allowing the monomer to be polymerized to polymerize in thepresence of the amine, where the lanthanide compound is a lanthanidecarboxylate, lanthanide organophosphate, lanthanide organophosphonate,lanthanide organophosphinate, lanthanide carbamate, lanthanidedithiocarbamate, lanthanide xanthate, lanthanide β-diketonate,lanthanide alkoxide or aryloxide, or organolanthanide compound, and theamine is introduced before 3% of the conjugated diene monomer that is tobe polymerized is polymerized.
 17. The method of claim 16, where thelanthanide-containing compound is neodymium formate, neodymium acetate,neodymium acrylate, neodymium methacrylate, neodymium valerate,neodymium gluconate, neodymium citrate, neodymium fumarate, neodymiumlactate, neodymium maleate, neodymium oxalate, neodymium2-ethylhexanoate, neodymium neodecanoate (a.k.a., neodymium versatate),neodymium naphthenate, neodymium stearate, neodymium oleate, neodymiumbenzoate, or neodymium picolinate.
 18. The method of claim 16, where thelanthanide-containing compound is neodymium dibutyl phosphate, neodymiumdipentyl phosphate, neodymium dihexyl phosphate, neodymium diheptylphosphate, neodymium dioctyl phosphate, neodymium bis(1-methylheptyl)phosphate, neodymium bis(2-ethylhexyl) phosphate, neodymium didecylphosphate, neodymium didodecyl phosphate, neodymium dioctadecylphosphate, neodymium dioleyl phosphate, neodymium diphenyl phosphate,neodymium bis(p-nonylphenyl) phosphate, neodymium butyl (2-ethylhexyl)phosphate, neodymium (1-methylheptyl) (2-ethylhexyl) phosphate, orneodymium (2-ethylhexyl) (p-nonylphenyl) phosphate.
 19. The method ofclaim 16, where the lanthanide-containing compound is neodymium butylphosphonate, neodymium pentyl phosphonate, neodymium hexyl phosphonate,neodymium heptyl phosphonate, neodymium octyl phosphonate, neodymium(1-methylheptyl) phosphonate, neodymium (2-ethylhexyl) phosphonate,neodymium decyl phosphonate, neodymium dodecyl phosphonate, neodymiumoctadecyl phosphonate, neodymium oleyl phosphonate, neodymium phenylphosphonate, neodymium (p-nonylphenyl) phosphonate, neodymium butylbutylphosphonate, neodymium pentyl pentylphosphonate, neodymium hexylhexylphosphonate, neodymium heptyl heptylphosphonate, neodymium octyloctylphosphonate, neodymium (1-methylheptyl) (1-methylheptyl)phosphonate, neodymium (2-ethylhexyl) (2-ethylhexyl) phosphonate,neodymium decyl decylphosphonate, neodymium dodecyl dodecylphosphonate,neodymium octadecyl octadecylphosphonate, neodymium oleyloleylphosphonate, neodymium phenyl phenylphosphonate, neodymium(p-nonylphenyl) (p-nonylphenyl) phosphonate, neodymium butyl(2-ethylhexyl) phosphonate, neodymium (2-ethylhexyl) butylphosphonate,neodymium (1-methylheptyl) (2-ethylhexyl)phosphonate, neodymium(2-ethylhexyl) (1-methylheptyl)phosphonate, neodymium (2-ethylhexyl)(p-nonylphenyl)phosphonate, or neodymium (p-nonylphenyl) (2-ethylhexyl)phosphonate.
 20. The method of claim 16, where the lanthanide-containingcompound is neodymium butylphosphinate, neodymium pentylphosphinate,neodymium hexylphosphinate, neodymium heptylphosphinate, neodymiumoctylphosphinate, neodymium (1-methylheptyl)phosphinate, neodymium(2-ethylhexyl)phosphinate, neodymium decylphosphinate, neodymiumdodecylphosphinate, neodymium octadecylphosphinate, neodymiumoleylphosphinate, neodymium phenylphosphinate, neodymium(p-nonylphenyl)phosphinate, neodymium dibutylphosphinate, neodymiumdipentylphosphinate, neodymium dihexylphosphinate, neodymiumdiheptylphosphinate, neodymium dioctylphosphinate, neodymiumbis(1-methylheptyl)phosphinate, neodymium bis(2-ethylhexyl)phosphinate,neodymium didecylphosphinate, neodymium didodecylphosphinate, neodymiumdioctadecylphosphinate, neodymium dioleylphosphinate, neodymiumdiphenylphosphinate, neodymium bis(p-nonylphenyl) phosphinate, neodymiumbutyl (2-ethylhexyl) phosphinate, neodymium (1-methylheptyl)(2-ethylhexyl) phosphinate, or neodymium (2-ethylhexyl)(p-nonylphenyl)phosphinate.